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Xiao-Qun Z, Xian-Li M, Ariffin NS. The potential of carbonic anhydrase enzymes as a novel target for anti-cancer treatment. Eur J Pharmacol 2024; 976:176677. [PMID: 38825301 DOI: 10.1016/j.ejphar.2024.176677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 05/15/2024] [Accepted: 05/27/2024] [Indexed: 06/04/2024]
Abstract
Carbonic anhydrase (CA) is a zinc-dependent metal enzyme that maintains the pH and carbon dioxide (CO2) homeostasis in cells by catalyzing the reversible hydration and dehydration of CO2 and bicarbonate (HCO3-). In mammals, there are 16 isozymes of CA existed, namely CAI to CAXIV, but only 15 isozymes are found in humans except CAXV. Human CAs have highly conserved catalytic domains, all of which are distributed in different tissues and play important physiological roles. Changes in their functions may disrupt the typical distribution of CAs throughout human body and therefore CAs can be used as diagnostic biomarkers for many diseases. Furthermore, the expression of CAs is correlated to the progression of numerous tumors, therapeutic sensitivity and patient prognosis. In this review, we discuss thoroughly the structure of CAs, their functional activities in human physiology, dysregulations and diseases related to CAs, and different types of CA inhibitors that can reverse their dysregulation.
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Affiliation(s)
- Zhou Xiao-Qun
- Department of Pharmacology and Pharmaceutical Chemistry, Faculty of Pharmacy, Universiti Teknologi MARA, 42300, Bandar Puncak Alam, Selangor, Malaysia; Guilin Medical University, GuiLin, China
| | | | - Nur Syamimi Ariffin
- Department of Pharmacology and Pharmaceutical Chemistry, Faculty of Pharmacy, Universiti Teknologi MARA, 42300, Bandar Puncak Alam, Selangor, Malaysia.
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2
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Illes-Toth E, Cooper HJ. Probing the Fundamentals of Native Liquid Extraction Surface Analysis Mass Spectrometry of Proteins: Can Proteins Refold during Extraction? Anal Chem 2019; 91:12246-12254. [PMID: 31490666 PMCID: PMC7006963 DOI: 10.1021/acs.analchem.9b02075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Native ambient mass spectrometry has the potential for simultaneous analysis of native protein structure and spatial distribution within thin tissue sections. Notwithstanding sensitivity, this information can, in principle, be obtained for any protein present with no requirement for a priori knowledge of protein identity. To date, native ambient mass spectrometry has primarily made use of the liquid extraction surface analysis (LESA) sampling technique. Here, we address a fundamental question: Are the protein structures observed following native liquid extraction surface analysis representative of the protein structures within the substrate, or does the extraction process facilitate refolding (or unfolding)? Specifically, our aim was to determine whether protein-ligand complexes observed following LESA are indicative of complexes present in the substrate, or an artifact of the sampling process. The systems investigated were myoglobin and its noncovalently bound heme cofactor, and the Zn-binding protein carbonic anhydrase and its binding with ethoxzolamide. Charge state distributions, drift time profiles, and collision cross sections were determined by liquid extraction surface analysis ion mobility mass spectrometry of native and denatured proteins and compared with those obtained by direct infusion electrospray. The results show that it was not possible to refold denatured proteins with concomitant ligand binding (neither heme, zinc, nor ethoxzolamide) simply by use of native-like LESA solvents. That is, protein-ligand complexes were only observed by LESA MS when present in the substrate.
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Affiliation(s)
- Eva Illes-Toth
- School of Biosciences , University of Birmingham , Birmingham , B15 2TT , U.K
| | - Helen J Cooper
- School of Biosciences , University of Birmingham , Birmingham , B15 2TT , U.K
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3
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Thermodynamic, kinetic, and structural parameterization of human carbonic anhydrase interactions toward enhanced inhibitor design. Q Rev Biophys 2019; 51:e10. [PMID: 30912486 DOI: 10.1017/s0033583518000082] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The aim of rational drug design is to develop small molecules using a quantitative approach to optimize affinity. This should enhance the development of chemical compounds that would specifically, selectively, reversibly, and with high affinity interact with a target protein. It is not yet possible to develop such compounds using computational (i.e., in silico) approach and instead the lead molecules are discovered in high-throughput screening searches of large compound libraries. The main reason why in silico methods are not capable to deliver is our poor understanding of the compound structure-thermodynamics and structure-kinetics correlations. There is a need for databases of intrinsic binding parameters (e.g., the change upon binding in standard Gibbs energy (ΔGint), enthalpy (ΔHint), entropy (ΔSint), volume (ΔVintr), heat capacity (ΔCp,int), association rate (ka,int), and dissociation rate (kd,int)) between a series of closely related proteins and a chemically diverse, but pharmacophoric group-guided library of compounds together with the co-crystal structures that could help explain the structure-energetics correlations and rationally design novel compounds. Assembly of these data will facilitate attempts to provide correlations and train data for modeling of compound binding. Here, we report large datasets of the intrinsic thermodynamic and kinetic data including over 400 primary sulfonamide compound binding to a family of 12 catalytically active human carbonic anhydrases (CA). Thermodynamic parameters have been determined by the fluorescent thermal shift assay, isothermal titration calorimetry, and by the stopped-flow assay of the inhibition of enzymatic activity. Kinetic measurements were performed using surface plasmon resonance. Intrinsic thermodynamic and kinetic parameters of binding were determined by dissecting the binding-linked protonation reactions of the protein and sulfonamide. The compound structure-thermodynamics and kinetics correlations reported here helped to discover compounds that exhibited picomolar affinities, hour-long residence times, and million-fold selectivities over non-target CA isoforms. Drug-lead compounds are suggested for anticancer target CA IX and CA XII, antiglaucoma CA IV, antiobesity CA VA and CA VB, and other isoforms. Together with 85 X-ray crystallographic structures of 60 compounds bound to six CA isoforms, the database should be of help to continue developing the principles of rational target-based drug design.
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4
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Protective Role of Carbonic Anhydrases III and VII in Cellular Defense Mechanisms upon Redox Unbalance. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:2018306. [PMID: 30154947 PMCID: PMC6098850 DOI: 10.1155/2018/2018306] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 07/24/2018] [Indexed: 01/07/2023]
Abstract
Under oxidative stress conditions, several constitutive cellular defense systems are activated, which involve both enzymatic systems and molecules with antioxidant properties such as glutathione and vitamins. In addition, proteins containing reactive sulfhydryl groups may eventually undergo reversible redox modifications whose products act as protective shields able to avoid further permanent molecular oxidative damage either in stressful conditions or under pathological circumstances. After the recovery of normal redox conditions, the reduced state of protein sulfhydryl groups is restored. In this context, carbonic anhydrases (CAs) III and VII, which are human metalloenzymes catalyzing the reversible hydration of carbon dioxide to bicarbonate and proton, have been identified to play an antioxidant role in cells where oxidative damage occurs. Both proteins are mainly localized in tissues characterized by a high rate of oxygen consumption, and contain on their molecular surface two reactive cysteine residues eventually undergoing S-glutathionylation. Here, we will provide an overview on the molecular and functional features of these proteins highlighting their implications into molecular processes occurring during oxidative stress conditions.
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5
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Monti DM, De Simone G, Langella E, Supuran CT, Di Fiore A, Monti SM. Insights into the role of reactive sulfhydryl groups of Carbonic Anhydrase III and VII during oxidative damage. J Enzyme Inhib Med Chem 2016; 32:5-12. [PMID: 27766895 PMCID: PMC6010095 DOI: 10.1080/14756366.2016.1225046] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Carbonic anhydrases (CAs) III and VII are two cytosolic isoforms of the α-CA family which catalyze the physiological reaction of carbon dioxide hydration to bicarbonate and proton. Despite these two enzymes share a 49% sequence identity and present a very similar three-dimensional structure, they show profound differences when comparing the specific activity for CO2 hydration reaction, with CA VII being much more active than CA III. Recently, CA III and CA VII have been proposed to play a new role as scavenger enzymes in cells where oxidative damage occurs. Here, we will examine functional and structural features of these two isoforms giving insights into their newly proposed protective role against oxidative stress.
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Affiliation(s)
- Daria M Monti
- a Department of Chemical Sciences , University of Naples Federico II , Naples , Italy
| | | | - Emma Langella
- b Institute of Biostructures and Bioimaging, CNR , Naples , Italy
| | - Claudiu T Supuran
- c Dipartimento Neurofarba, Sezione di Scienze Farmaceutiche e Nutraceutiche , Università degli Studi di Firenze , Florence , Italy
| | - Anna Di Fiore
- b Institute of Biostructures and Bioimaging, CNR , Naples , Italy
| | - Simona M Monti
- b Institute of Biostructures and Bioimaging, CNR , Naples , Italy
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6
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De Simone G, Di Fiore A, Capasso C, Supuran CT. The zinc coordination pattern in the η-carbonic anhydrase from Plasmodium falciparum is different from all other carbonic anhydrase genetic families. Bioorg Med Chem Lett 2015; 25:1385-9. [PMID: 25765908 DOI: 10.1016/j.bmcl.2015.02.046] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 02/19/2015] [Accepted: 02/22/2015] [Indexed: 12/19/2022]
Abstract
In this Letter we reinvestigate the sequence analysis and report a homology model of the carbonic anhydrase (CA, EC 4.2.1.1) from the protozoan parasite Plasmodium falciparum, recently reported by us to belong to a new genetic family, the η-CA class. Our findings show that the metal ion coordination pattern of this CA is unique among all five other genetic families encoding for such enzymes, comprising two His and one Gln residues, in addition to the water molecule/hydroxide ion acting as nucleophile in the catalytic cycle. Although the η- and α-CAs present the same 3D fold, strongly suggesting the first ones to be evolutionary derived from the last, there are significant differences between the two families to allow optimism for the drug design of selective inhibitors for the parasite over the host enzymes. The preliminary studies reported here are relevant for drug design campaigns of anti-plasmodium CA inhibitors but further work by X-ray crystallography should validate the proposed model.
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Affiliation(s)
- Giuseppina De Simone
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Napoli, Italy
| | - Anna Di Fiore
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Napoli, Italy
| | - Clemente Capasso
- Istituto di Bioscienze e Biorisorse, CNR, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Claudiu T Supuran
- Università degli Studi di Firenze, Dipartimento Neurofarba, Sezione di Scienze Farmaceutiche, and Laboratorio di Chimica Bioinorganica, Polo Scientifico, Via U. Schiff 6, 50019 Sesto Fiorentino, Florence, Italy.
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7
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Alka K, Casey JR. Bicarbonate transport in health and disease. IUBMB Life 2014; 66:596-615. [PMID: 25270914 DOI: 10.1002/iub.1315] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/10/2014] [Indexed: 12/28/2022]
Abstract
Bicarbonate (HCO3(-)) has a central place in human physiology as the waste product of mitochondrial energy production and for its role in pH buffering throughout the body. Because bicarbonate is impermeable to membranes, bicarbonate transport proteins are necessary to enable control of bicarbonate levels across membranes. In humans, 14 bicarbonate transport proteins, members of the SLC4 and SLC26 families, function by differing transport mechanisms. In addition, some anion channels and ZIP metal transporters contribute to bicarbonate movement across membranes. Defective bicarbonate transport leads to diseases, including systemic acidosis, brain dysfunction, kidney stones, and hypertension. Altered expression levels of bicarbonate transporters in patients with breast, colon, and lung cancer suggest an important role of these transporters in cancer.
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Affiliation(s)
- Kumari Alka
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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8
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Karthik D, Ilavenil S, Kaleeswaran B, Ravikumar S. Analysis of Modification of Liver Proteome in Diabetic Rats by 2D Electrophoresis and MALDI-TOF-MS. Indian J Clin Biochem 2012; 27:221-30. [PMID: 26405379 PMCID: PMC4577502 DOI: 10.1007/s12291-012-0209-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 03/26/2012] [Indexed: 01/28/2023]
Abstract
The uncontrolled hyperglycemia can lead to disturbances in the cell structure and functions of organs. This study was performed to analyze the "differential proteome" change in rat liver associated with diabetes mellitus in relation to effects of an anti-diabetic herb, Cynodon dactylon leaf extracts. Rats were intraperitoneally injected with alloxan (150 mg/kg/bw) and treated with C. dactylon leaf extracts (450 mg/kg/bw/day/orally). The liver proteins were subjected to proteome analysis using the advanced technologies i.e., 2D electrophoresis (2-DE) and mass spectrometry. Comparison of 2-DE protein distribution profiles among the livers from normal, alloxan-induced diabetic rats and alloxan-induced diabetic rats treated with C. dactylon leaves identified three proteins that were up-regulated in alloxan-induced diabetic rats i.e., nucleophosmin, l-xylulose reductase and carbonic anhydrase III which are known to be mainly involved in ribosome biogenesis, centrosome duplication, cell proliferation, tumor suppression, glucose metabolism, osmo-regulation, water-CO2 balance and acid-base balance. These results help us to understand the elucidation of molecular mechanism connected to liver function and insulin associated with diabetes mellitus. These identified proteins were primarily involved in cell proliferation and homoeostasis of liver tissues upon the treatment with C. dactylon leaf extracts.
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Affiliation(s)
- Dhanaraj Karthik
- Department of Biotechnology, Faculty of Biotechnology, PRIST University, Thanjavur, 613 403 Tamil Nadu India
| | - Soundherrajan Ilavenil
- Department of Biotechnology, Faculty of Biotechnology, PRIST University, Thanjavur, 613 403 Tamil Nadu India
| | - Balasubramanian Kaleeswaran
- Department of Biotechnology, Faculty of Biotechnology, PRIST University, Thanjavur, 613 403 Tamil Nadu India
| | - Sivanesan Ravikumar
- Department of Biotechnology, Faculty of Biotechnology, PRIST University, Thanjavur, 613 403 Tamil Nadu India
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9
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Alterio V, Di Fiore A, D'Ambrosio K, Supuran CT, De Simone G. Multiple binding modes of inhibitors to carbonic anhydrases: how to design specific drugs targeting 15 different isoforms? Chem Rev 2012; 112:4421-68. [PMID: 22607219 DOI: 10.1021/cr200176r] [Citation(s) in RCA: 932] [Impact Index Per Article: 77.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Vincenzo Alterio
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Napoli, Italy
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10
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Imtaiyaz Hassan M, Shajee B, Waheed A, Ahmad F, Sly WS. Structure, function and applications of carbonic anhydrase isozymes. Bioorg Med Chem 2012; 21:1570-82. [PMID: 22607884 DOI: 10.1016/j.bmc.2012.04.044] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/02/2012] [Accepted: 04/21/2012] [Indexed: 01/16/2023]
Abstract
The carbonic anhydrases enzymes (CAs, EC 4.2.1.1) are zinc containing metalloproteins, which efficiently catalyse the reversible conversion of carbon dioxide to bicarbonate and release proton. These enzymes are essentially important for biological system and play several important physiological and patho-physiological functions. There are 16 different alpha-carbonic anhydrase isoforms studied, differing widely in their cellular localization and biophysical properties. The catalytic domains of all CAs possess a conserved tertiary structure fold, with predominately β-strands. We performed an extensive analysis of all 16 mammalian CAs for its structure and function in order to establish a structure-function relationship. CAs have been a potential therapeutic target for many diseases. Sulfonamides are considered as a strong and specific inhibitor of CA, and are being used as diuretics, anti-glaucoma, anti-epileptic, anti-ulcer agents. Currently CA inhibitors are widely used as a drug for the treatment of neurological disorders, anti-glaucoma drugs, anti-cancer, or anti-obesity agents. Here we tried to emphasize how CAs can be used for drug discovery, design and screening. Furthermore, we discussed the role of CA in carbon capture, carbon sensor and metabolon. We hope this review provide many useful information on structure, function, mechanism, and applications of CAs in various discipline.
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Affiliation(s)
- Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
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11
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Melnik BS, Molochkov NV, Prokhorov DA, Uversky VN, Kutyshenko VP. Molecular mechanisms of the anomalous thermal aggregation of green fluorescent protein. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1930-9. [DOI: 10.1016/j.bbapap.2011.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 07/19/2011] [Accepted: 07/19/2011] [Indexed: 11/27/2022]
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12
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Schueler C, Becker HM, McKenna R, Deitmer JW. Transport activity of the sodium bicarbonate cotransporter NBCe1 is enhanced by different isoforms of carbonic anhydrase. PLoS One 2011; 6:e27167. [PMID: 22076132 PMCID: PMC3208603 DOI: 10.1371/journal.pone.0027167] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 10/11/2011] [Indexed: 12/31/2022] Open
Abstract
Transport metabolons have been discussed between carbonic anhydrase II (CAII) and several membrane transporters. We have now studied different CA isoforms, expressed in Xenopus oocytes alone and together with the electrogenic sodium bicarbonate cotransporter 1 (NBCe1), to determine their catalytic activity and their ability to enhance NBCe1 transport activity. pH measurements in intact oocytes indicated similar activity of CAI, CAII and CAIII, while in vitro CAIII had no measurable activity and CAI only 30% of the activity of CAII. All three CA isoforms increased transport activity of NBCe1, as measured by the transport current and the rate of intracellular sodium rise in oocytes. Two CAII mutants, altered in their intramolecular proton pathway, CAII-H64A and CAII-Y7F, showed significant catalytic activity and also enhanced NBCe1 transport activity. The effect of CAI, CAII, and CAII mutants on NBCe1 activity could be reversed by blocking CA activity with ethoxyzolamide (EZA, 10 µM), while the effect of the less EZA-sensitive CAIII was not reversed. Our results indicate that different CA isoforms and mutants, even if they show little enzymatic activity in vitro, may display significant catalytic activity in intact cells, and that the ability of CA to enhance NBCe1 transport appears to depend primarily on its catalytic activity.
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Affiliation(s)
- Christina Schueler
- Abteilung für Allgemeine Zoologie, FB Biologie, TU Kaiserslautern, Kaiserslautern, Germany.
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Intramolecular proton shuttle supports not only catalytic but also noncatalytic function of carbonic anhydrase II. Proc Natl Acad Sci U S A 2011; 108:3071-6. [PMID: 21282642 DOI: 10.1073/pnas.1014293108] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Carbonic anhydrases (CAs) catalyze the reversible hydration of CO(2) to HCO(3)(-) and H(+). The rate-limiting step in this reaction is the shuttle of protons between the catalytic center of the enzyme and the bulk solution. In carbonic anhydrase II (CAII), the fastest and most wide-spread isoform, this H(+) shuttle is facilitated by the side chain of His64, whereas CA isoforms such as carbonic anhydrase III (CAIII), which lack such a shuttle, have only low catalytic activity in vitro. By using heterologous protein expression in Xenopus oocytes, we tested the role of this intramolecular H(+) shuttle on CA activity in an intact cell. The data revealed that CAIII, shown in vitro to have ∼1,000-fold reduced activity as compared with CAII, displays significant catalytic activity in the intact cell. Furthermore, we tested the hypothesis that the H(+) shuttle in CAII itself can facilitate transport activity of the monocarboxylate transporters 1 and 4 (MCT1/4) independent of catalytic activity. Our results show that His64 is essential for the enhancement of lactate transport via MCT1/4, because a mutation of this residue to alanine (CAII-H64A) abolishes the CAII-induced increase in MCT1/4 activity. However, injection of 4-methylimidazole, which acts as an exogenous H(+) donor/acceptor, can restore the ability of CAII-H64A to enhance transport activity of MCT1/4. These findings support the hypothesis that the H(+) shuttle in CAII not only facilitates CAII catalytic activity but also can enhance activity of acid-/base-transporting proteins such as MCT1/4 in a direct, noncatalytic manner, possibly by acting as an "H(+)-collecting antenna."
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14
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Di Fiore A, Truppo E, Supuran CT, Alterio V, Dathan N, Bootorabi F, Parkkila S, Monti SM, De Simone G. Crystal structure of the C183S/C217S mutant of human CA VII in complex with acetazolamide. Bioorg Med Chem Lett 2010; 20:5023-6. [PMID: 20688517 DOI: 10.1016/j.bmcl.2010.07.051] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 07/12/2010] [Accepted: 07/12/2010] [Indexed: 10/19/2022]
Abstract
Human carbonic anhydrase VII (hCA VII) is a cytosolic member of the alpha-CA family. This enzyme is mainly localized in a number of brain tissues such as the cortex, hippocampus and thalamus and has been noted for its contribution in generating neuronal excitation and seizures. Recently, it has been also proposed that hCA VII may be involved in the control of neuropathic pain, thus its inhibition may offer a new approach in designing pain killers useful for combating neuropathic pain. We report here the X-ray crystallographic structure of a mutated form of human CA VII in complex with acetazolamide, a classical sulfonamide inhibitor. These crystallographic studies provide important implications for the rational drug design of selective CA inhibitors with clinical applications.
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Affiliation(s)
- Anna Di Fiore
- Istituto di Biostrutture e Bioimmagini-CNR, Napoli, Italy
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15
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Alterio V, Monti SM, Truppo E, Pedone C, Supuran CT, De Simone G. The first example of a significant active site conformational rearrangement in a carbonic anhydrase-inhibitor adduct: the carbonic anhydrase I-topiramate complex. Org Biomol Chem 2010; 8:3528-33. [PMID: 20505865 DOI: 10.1039/b926832d] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Topiramate is a widely used antiepileptic drug, which has been demonstrated to act as an efficient weight loss agent. Since several studies have pointed out that is a potent in vitro inhibitor of several Carbonic anhydrase (CA) isozymes, it has been hypothesized that its anti-obesity properties could be ascribed to the inhibition of the CAs involved in de novo lipogenesis. Consequently, the study of the interactions of with all human CA isoforms represents an important step for the rational drug design of selective CA inhibitors to be used as anti-obesity drugs. In this paper we report the crystallographic structure of the adduct that forms with hCA I, showing for the first time a profound reorganization of the CA active site upon binding of the inhibitor. Moreover, a structural comparison with hCA II- and hCA VA- adducts, previously investigated, has been performed showing that a different H-bond network together with the movement of some amino acid residues in the active site may account for the different inhibition constants of toward these three CA isozymes.
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Affiliation(s)
- Vincenzo Alterio
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Naples, Italy
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16
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Crystal structure of the catalytic domain of the tumor-associated human carbonic anhydrase IX. Proc Natl Acad Sci U S A 2009; 106:16233-8. [PMID: 19805286 DOI: 10.1073/pnas.0908301106] [Citation(s) in RCA: 379] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Carbonic anhydrase (CA) IX is a plasma membrane-associated member of the alpha-CA enzyme family, which is involved in solid tumor acidification. It is a marker of tumor hypoxia and a prognostic factor in several human cancers. An aberrant increase in CA IX expression in chronic hypoxia and during development of various carcinomas contributes to tumorigenesis through at least two mechanisms: pH regulation and cell adhesion control. Here we report the X-ray structure of the catalytic domain of CA IX in complex with a classical, clinically used sulfonamide inhibitor, acetazolamide. The structure reveals a typical alpha-CA fold, which significantly differs from the other CA isozymes when the protein quaternary structure is considered. Thus, two catalytic domains of CA IX associate to form a dimer, which is stabilized by the formation of an intermolecular disulfide bond. The active site clefts and the PG domains are located on one face of the dimer, while the C-termini are located on the opposite face to facilitate protein anchoring to the cell membrane. A correlation between the three-dimensional structure and the physiological role of the enzyme is here suggested, based on the measurement of the pH profile of the catalytic activity for the physiological reaction, CO(2) hydration to bicarbonate and protons. On the basis of the structural differences observed between CA IX and the other membrane-associated alpha-CAs, further prospects for the rational drug design of isozyme-specific CA inhibitors are proposed, given that inhibition of this enzyme shows antitumor activity both in vitro and in vivo.
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17
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Hill SE, Bandaria JN, Fox M, Vanderah E, Kohen A, Cheatum CM. Exploring the molecular origins of protein dynamics in the active site of human carbonic anhydrase II. J Phys Chem B 2009; 113:11505-10. [PMID: 19637848 PMCID: PMC2736349 DOI: 10.1021/jp901321m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We present three-pulse vibrational echo measurements of azide ion bound to the active site Zn of human carbonic anhydrase II (HCA II) and of two separate active-site mutants Thr199 --> Ala (T199A) and Leu198 --> Phe (L198F). Because structural motions of the protein active site influence the frequency of bound ligands, the differences in the time scales of the frequency-frequency correlation functions (FFCFs) obtained from global fits to each set of data allow us to make inferences about the time scales of the active site dynamics of HCA II. Surprisingly, the deletion of a potential electrostatic interaction in results in very little change in the FFCF, but the insertion of the bulky phenylalanine ring in causes much faster dynamics. We conclude that the fast, sub-picosecond time scale in the correlation function is attributable to hydrogen bond dynamics, and the slow, apparently static contribution is due to the conformational flexibility of Zn-bound azide in the active site.
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Affiliation(s)
- Sarah E Hill
- Department of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242, USA.
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18
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Nishimori I, Minakuchi T, Onishi S, Vullo D, Cecchi A, Scozzafava A, Supuran CT. Carbonic anhydrase inhibitors. Cloning, characterization and inhibition studies of the cytosolic isozyme III with anions. J Enzyme Inhib Med Chem 2008; 24:70-6. [DOI: 10.1080/14756360801907143] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Isao Nishimori
- Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku 783-8505, Kochi, Japan
| | - Tomoko Minakuchi
- Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku 783-8505, Kochi, Japan
| | - Saburo Onishi
- Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku 783-8505, Kochi, Japan
| | - Daniela Vullo
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, Sesto Fiorentino (Firenze) I-50019, Italy
| | - Alessandro Cecchi
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, Sesto Fiorentino (Firenze) I-50019, Italy
| | - Andrea Scozzafava
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, Sesto Fiorentino (Firenze) I-50019, Italy
| | - Claudiu T. Supuran
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, Sesto Fiorentino (Firenze) I-50019, Italy
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Vullo D, Nishimori I, Scozzafava A, Supuran CT. Carbonic anhydrase activators: Activation of the human cytosolic isozyme III and membrane-associated isoform IV with amino acids and amines. Bioorg Med Chem Lett 2008; 18:4303-7. [DOI: 10.1016/j.bmcl.2008.06.075] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Revised: 06/24/2008] [Accepted: 06/25/2008] [Indexed: 11/24/2022]
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20
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Prokhorov DA, Timchenko AA, Uversky VN, Khristoforov VS, Kihara H, Kimura K, Kutyshenko VP. Dynamics of oligomer formation by denatured carbonic anhydrase II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:834-42. [DOI: 10.1016/j.bbapap.2008.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 02/14/2008] [Accepted: 02/20/2008] [Indexed: 10/22/2022]
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21
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Krishnamurthy VM, Kaufman GK, Urbach AR, Gitlin I, Gudiksen KL, Weibel DB, Whitesides GM. Carbonic anhydrase as a model for biophysical and physical-organic studies of proteins and protein-ligand binding. Chem Rev 2008; 108:946-1051. [PMID: 18335973 PMCID: PMC2740730 DOI: 10.1021/cr050262p] [Citation(s) in RCA: 561] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Vijay M. Krishnamurthy
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - George K. Kaufman
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - Adam R. Urbach
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - Irina Gitlin
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - Katherine L. Gudiksen
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - Douglas B. Weibel
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
| | - George M. Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
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22
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Nishimori I, Minakuchi T, Onishi S, Vullo D, Cecchi A, Scozzafava A, Supuran CT. Carbonic anhydrase inhibitors: Cloning, characterization, and inhibition studies of the cytosolic isozyme III with sulfonamides. Bioorg Med Chem 2007; 15:7229-36. [PMID: 17826101 DOI: 10.1016/j.bmc.2007.08.037] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 07/30/2007] [Accepted: 08/21/2007] [Indexed: 10/22/2022]
Abstract
The cytosolic human carbonic anhydrase (hCA, EC 4.2.1.1) isozyme III (hCA III) has been cloned and purified by the GST-fusion protein method. Recombinant pure hCA III had the following kinetic parameters for the CO(2) hydration reaction at 20 degrees C and pH 7.5: k(cat) of 1.3 x 10(4) s(-1) and k(cat)/K(M) of 2.5 x 10(5) M(-1) s(-1), being a slower catalyst for the physiological reaction as compared to the genetically related cytosolic isoforms hCA I and II. An inhibition study with a library of sulfonamides and one sulfamate, some which are clinically used compounds, is reported. hCA III is less prone to be inhibited by these compounds as compared to hCA I and II for which many low nanomolar inhibitors were detected earlier. The best hCA III inhibitors were prontosil, sulpiride, indisulam, benzolamide, aminobenzolamide, and 4-amino-6-chloro-benzene-1,3-disulfonamide which showed K(I)s in the range of 2.3-18.1 microM. Clinically used compounds such as acetazolamide, methazolamide, ethoxzolamide, dorzolamide, brinzolamide, topiramate, zonisamide, celecoxib, and valdecoxib were less effective hCA III inhibitors, with affinities in the range of 154-2200 microM. This is the first study in which low micromolar hCA III inhibitors are reported.
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Affiliation(s)
- Isao Nishimori
- Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
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23
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Abstract
Considerable attention has been focused on proton transfer through intervening water molecules in complex macromolecules of biological interest, such as bacteriorhodopsin, cytochrome c oxidase, and many others. Proton transfer in catalysis by carbonic anhydrase provides a useful model for the study of the properties of such proton translocations. High-resolution X-ray crystallography in combination with measurements of catalysis have revealed new details of this process. A prominent proton shuttle residue His64 shows evidence of structural mobility, which appears to enhance proton transfer between the active site and bulk solvent. Moreover, the properties of the imidazole side chain of His64, including its conformations and pK(a), are finely tuned by surrounding residues of the active-site cavity. The structure of a network of ordered solvent molecules located between His64 and the active site are also sensitive to surrounding residues. These features combine to provide efficient proton-transfer rates as great as 10(6) s(-1) necessary to sustain rapid catalysis.
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Affiliation(s)
- David N Silverman
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
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24
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Supuran CT, Scozzafava A. Carbonic anhydrases as targets for medicinal chemistry. Bioorg Med Chem 2007; 15:4336-50. [PMID: 17475500 DOI: 10.1016/j.bmc.2007.04.020] [Citation(s) in RCA: 427] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 04/10/2007] [Accepted: 04/13/2007] [Indexed: 01/27/2023]
Abstract
Carbonic anhydrases (CAs, EC 4.2.1.1) are zinc enzymes acting as efficient catalysts for the reversible hydration of carbon dioxide to bicarbonate. 16 different alpha-CA isoforms were isolated in mammals, where they play crucial physiological roles. Some of them are cytosolic (CA I, CA II, CA III, CA VII, CA XIII), others are membrane-bound (CA IV, CA IX, CA XII, CA XIV and CA XV), CA VA and CA VB are mitochondrial, and CA VI is secreted in saliva and milk. Three acatalytic forms are also known, the CA related proteins (CARP), CARP VIII, CARP X and CARP XI. Representatives of the beta-delta-CA family are highly abundant in plants, diatoms, eubacteria and archaea. The catalytic mechanism of the alpha-CAs is understood in detail: the active site consists of a Zn(II) ion co-ordinated by three histidine residues and a water molecule/hydroxide ion. The latter is the active species, acting as a potent nucleophile. For beta- and gamma-CAs, the zinc hydroxide mechanism is valid too, although at least some beta-class enzymes do not have water directly coordinated to the metal ion. CAs are inhibited primarily by two classes of compounds: the metal complexing anions and the sulfonamides/sulfamates/sulfamides possessing the general formula RXSO(2)NH(2) (R=aryl; hetaryl; perhaloalkyl; X=nothing, O or NH). Several important physiological and physio-pathological functions are played by CAs present in organisms all over the phylogenetic tree, related to respiration and transport of CO(2)/bicarbonate between metabolizing tissues and the lungs, pH and CO(2) homeostasis, electrolyte secretion in a variety of tissues/organs, biosynthetic reactions, such as the gluconeogenesis and ureagenesis among others (in animals), CO(2) fixation (in plants and algae), etc. The presence of these ubiquitous enzymes in so many tissues and in so different isoforms represents an attractive goal for the design of inhibitors with biomedical applications. Indeed, CA inhibitors are clinically used as antiglaucoma drugs, some other compounds being developed as antitumour agents/diagnostic tools for tumours, antiobesity agents, anticonvulsants and antimicrobials/antifungals (inhibitors targeting alpha- or beta-CAs from pathogenic organisms such as Helicobacter pylori, Mycobacterium tuberculosis, Plasmodium falciparum, Candida albicans, etc.).
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Affiliation(s)
- Claudiu T Supuran
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, I-50019 Sesto Fiorentino (Firenze), Italy.
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25
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Elder I, Fisher Z, Laipis PJ, Tu C, McKenna R, Silverman DN. Structural and kinetic analysis of proton shuttle residues in the active site of human carbonic anhydrase III. Proteins 2007; 68:337-43. [PMID: 17427958 DOI: 10.1002/prot.21403] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We report the X-ray crystal structures and rate constants for proton transfer in site-specific mutants of human carbonic anhydrase III (HCA III) that place a histidine residue in the active-site cavity: K64H, R67H, and K64H-R67N HCA III. Prior evidence from the exchange of 18O between CO2 and water measured by mass spectrometry shows each mutant to have enhanced proton transfer in catalysis compared with wild-type HCA III. However, His64 in K64H and K64H-R67N HCA III have at most a capacity for proton transfer that is only 13% that of His64 in HCA II. This reduced rate in mutants of HCA III is associated with a constrained side-chain conformation of His64, which is oriented outward, away from the active-site zinc in the crystal structures. This conformation appears stabilized by a prominent pi stacking interaction of the imidazole ring of His64 with the indole ring of Trp5 in mutants of HCA III. This single orientation of His64 in K64H HCA III predominates also in a double mutant K64H-R67N HCA III, indicating that the positive charge of Arg67 does not influence the observed conformation of His64 in the crystal structure. Hence, the structures and catalytic activity of these mutants of HCA III containing His64 account only in small part for the lower activity of this isozyme compared with HCA II. His67 in R67H HCA III was also shown to be a proton shuttle residue, having a capacity for proton transfer that was approximately four times that of His64 in K64H HCA III. This is most likely due to its proximity and orientation inward towards the zinc-bound solvent. These results emphasize the significance of side chain orientation and range of available conformational states as characteristics of an efficient proton shuttle in carbonic anhydrase.
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Affiliation(s)
- Ileana Elder
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610-0267, USA
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26
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Abstract
Carbonic anhydrase 3 is easily S-glutathionylated in vivo and in vitro. The protein has two surface-exposed cysteine residues that can be modified. We found that Cys186 is more readily glutathionylated than Cys181. We studied a series of site-specific mutants to identify the residues that interact with Cys186 to make its thiol more reactive. We found that Lys211 is responsible for lowering the pKa of Cys186. We also found that two acidic residues, Asp188 and Glu212, interact with the thiol and actually decrease its reactivity. We speculate that conformational changes that alter the interaction with these three residues provide a mechanistic basis for modulation of the susceptibility of carbonic anhydrase 3 to glutathionylation.
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Affiliation(s)
- Geumsoo Kim
- Laboratory of Biochemistry, National Heart, Lung and Blood Institute, Bethesda, MD 20892-0812, USA
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27
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28
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Gao X, Butler IS, Kremer R. A near-infrared Fourier transform Raman spectroscopy of epidermal keratinocytes: changes in the protein-DNA structure following malignant transformation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:27-35. [PMID: 15556417 DOI: 10.1016/j.saa.2004.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2003] [Revised: 12/19/2003] [Accepted: 03/15/2004] [Indexed: 05/24/2023]
Abstract
We report here the use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy to analyze normal human epidermal keratinocytes prior to and following malignant transformation. Our analysis indicates specific Raman spectral differences between immortalized (HPK1A) and malignant ras transformed (HPK1A-ras) cells. In addition, striking spectral differences are seen in the DNA isolated from these cells and particularly in the 843/810 cm(-1) ratio with values of 1.6 +/- 0.13 in HPK1A cells and 0.68 +/- 0.09 in HPK1A-ras cells (mean +/- S.D., n = 12, P < 0.001) indicating specific alterations in the backbone conformation markers following malignant transformation. Subsequently, we analysed the effect of a strong inhibitor of keratinocyte growth, the Vitamin D analog EB1089, on the Raman spectra of intact cells and on the 843/810 cm(-1) ratio in the DNA isolated from both cell lines. Specific changes were observed in intact cells in the 1300-750 cm(-1) region. Furthermore, the 843/810 cm(-1) ratio of isolated DNA from HPK1A cells was not affected by EB1089 but significantly increased in DNA isolated from HPK1A-ras cells so much that it became closer to the value observed for HPK1A cells (1.07 +/- 0.10). Our data suggest that Raman analysis of DNA and in particular the 843/810 cm(-1) ratio can provide useful indices of malignant transformation and efficacy of anticancer agents.
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Affiliation(s)
- Xiaoling Gao
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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29
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Shi Z, Woody RW, Kallenbach NR. Is polyproline II a major backbone conformation in unfolded proteins? ADVANCES IN PROTEIN CHEMISTRY 2004; 62:163-240. [PMID: 12418104 DOI: 10.1016/s0065-3233(02)62008-x] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Zhengshuang Shi
- Department of Chemistry, New York University, New York 10003, USA
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30
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Elder I, Han S, Tu C, Steele H, Laipis PJ, Viola RE, Silverman DN. Activation of carbonic anhydrase II by active-site incorporation of histidine analogs. Arch Biochem Biophys 2004; 421:283-9. [PMID: 14984209 DOI: 10.1016/j.abb.2003.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The hydration of CO2 catalyzed by human carbonic anhydrase II (HCA II) is accompanied by proton transfer from the zinc-bound water of the enzyme to solution. We have replaced the proton shuttling residue His 64 with Ala and placed cysteine residues within the active-site cavity by mutating sites Trp 5, Asn 62, Ile 91, and Phe 131. These mutants were modified at the single inserted cysteine with imidazole analogs to introduce new potential shuttle groups. Catalysis by these modified mutants was determined by stopped-flow and 18O-exchange methods. Specificity in proton transfer was demonstrated; only modifications of the Cys 131-containing mutant showed enhancement in the proton transfer step of catalysis compared with unmodified Cys 131-containing mutant. Modifications at other sites resulted in up to 3-fold enhancement in rates of CO2 hydration, with apparent second-order rate constants near 350 microM(-1) s(-1). These are among the largest values of kcat/Km observed for a carbonic anhydrase.
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Affiliation(s)
- Ileana Elder
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL 32610-0267, USA
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31
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Knudsen B, Miyamoto MM, Laipis PJ, Silverman DN. Using evolutionary rates to investigate protein functional divergence and conservation. A case study of the carbonic anhydrases. Genetics 2003; 164:1261-9. [PMID: 12930737 PMCID: PMC1462676 DOI: 10.1093/genetics/164.4.1261] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Functional constraints on proteins limit their evolutionary rates at specific sites. These constraints allow for the interpretation of conserved residues and sites with a rate change as those most likely underlying the functional similarities and differences among protein subfamilies, respectively. This study describes new likelihood-ratio tests (LRTs) that complement existing ones for the identification of both conserved and rate change sites. These identifications are validated by the recovery of residues that are known from existing biochemical and structural information to be critical for the functional similarities and differences among carbonic anhydrases (CAs). In combination with this other information, these LRTs also support a unique antioxidant defense role for the puzzling CA III. As illustrated by the CAs, these LRTs, in combination with other biological evidence, offer a powerful and cost-effective approach for testing hypotheses, making predictions, and designing experiments in protein functional studies.
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Affiliation(s)
- Bjarne Knudsen
- Bioinformatics Research Center, University of Aarhus, 8000 Aarhus C, Denmark.
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32
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Gupta SP. Quantitative structure-activity relationships of carbonic anhydrase inhibitors. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2003; 60:171-204. [PMID: 12790343 DOI: 10.1007/978-3-0348-8012-1_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A review is presented of quantitative structure-activity relationships (QSARs) of different categories of carbonic anhydrase (CA) inhibitors, which are basically benzenesulfonamides, heterocyclic sulfonamides and aliphatic sulfonamides. The review shows that in all categories, the inhibition potency depends largely on the electronic properties of the sulfonamide group, which can be affected by the electronic characteristics of the substituents present on the nucleus (benzene or heterocyclic ring) of the sulfonamide molecules. Substituents themselves can be involved, along with the nucleus, in some dispersion interaction with the enzyme. Based on this review, a schematic model is presented to represent the interaction of sulfonamides with the CA.
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Affiliation(s)
- Satya P Gupta
- Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, India.
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33
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Abstract
At least 14 different carbonic anhydrase (CA, EC 4.2.1.1) isoforms were isolated in higher vertebrates, where these zinc enzymes play crucial physiological roles. Some of these isozymes are cytosolic (CA I, CA II, CA III, CA VII), others are membrane-bound (CA IV, CA IX, CA XII, and CA XIV), CA V is mitochondrial and CA VI is secreted in saliva. Three acatalytic forms are also known, which are denominated CA related proteins (CARP), CARP VIII, CARP X, and CARP XI. Several important physiological and physio-pathological functions are played by many CA isozymes, which are strongly inhibited by aromatic and heterocyclic sulfonamides as well as inorganic, metal complexing anions. The catalytic and inhibition mechanisms of these enzymes are understood in detail, and this helped the design of potent inhibitors, some of which possess important clinical applications. The use of such enzyme inhibitors as antiglaucoma drugs will be discussed in detail, together with the recent developments that led to isozyme-specific and organ-selective inhibitors. A recent discovery is connected with the involvement of CAs and their sulfonamide inhibitors in cancer: several potent sulfonamide inhibitors inhibited the growth of a multitude of tumor cells in vitro and in vivo, thus constituting interesting leads for developing novel antitumor therapies. Furthermore, some other classes of compounds that interact with CAs have recently been discovered, some of which possess modified sulfonamide or hydroxamate moieties. Some sulfonamides have also applications as diagnostic tools, in PET and MRI or as antiepileptics or for the treatment of other neurological disorders. Future prospects for drug design applications for inhibitors of these ubiquitous enzymes are also discussed.
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Affiliation(s)
- Claudiu T Supuran
- Dipartimento di Chimica, University of Florence, Via della Lastruccia 3, Rm 188, Polo Scientifico, 50019-Sesto Fiorentino (Firenze), Italy.
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34
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Ferraroni M, Briganti F, Chegwidden W, Supuran CT, Scozzafava A. Crystal analysis of aromatic sulfonamide binding to native and (Zn)2 adduct of human carbonic anhydrase I Michigan 1. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00959-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Tu C, Qian M, An H, Wadhwa NR, Duda D, Yoshioka C, Pathak Y, McKenna R, Laipis PJ, Silverman DN. Kinetic analysis of multiple proton shuttles in the active site of human carbonic anhydrase. J Biol Chem 2002; 277:38870-6. [PMID: 12171926 DOI: 10.1074/jbc.m205791200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have prepared a site-specific mutant of human carbonic anhydrase (HCA) II with histidine residues at positions 7 and 64 in the active site cavity. Using a different isozyme, we have placed histidine residues in HCA III at positions 64 and 67 and in another mutant at positions 64 and 7. Each of these histidine residues can act as a proton transfer group in catalysis when it is the only nonliganding histidine in the active site cavity, except His(7) in HCA III. Using an (18)O exchange method to measure rate constants for intramolecular proton transfer, we have found that inserting two histidine residues into the active site cavity of either isozyme II or III of carbonic anhydrase results in rates of proton transfer to the zinc-bound hydroxide that are antagonistic or suppressive with respect to the corresponding single mutants. The crystal structure of Y7H HCA II, which contains both His(7) and His(64) within the active site cavity, shows the conformation of the side chain of His(64) moved from its position in the wild type and hydrogen-bonded through an intervening water molecule with the side chain of His(7). This suggests a cause of decreased proton transfer in catalysis.
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Affiliation(s)
- Chingkuang Tu
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610-0267, USA
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36
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An H, Tu C, Ren K, Laipis PJ, Silverman DN. Proton transfer within the active-site cavity of carbonic anhydrase III. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1599:21-7. [PMID: 12484342 DOI: 10.1016/s0167-4838(02)00374-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The maximal turnover rate of CO2 hydration catalyzed by the carbonic anhydrases is limited by proton transfer steps from the zinc-bound water to solution, steps that regenerate the catalytically active zinc-bound hydroxide. Catalysis of CO2 hydration by wild-type human carbonic anhydrase III (HCA III) (k(cat) = 2 ms (-1)) is the least efficient among the carbonic anhydrases in its class, in part because it lacks an efficient proton shuttle residue. We have used site-directed mutagenesis to test positions within the active-site cavity of HCA III for their ability to carry out proton transfer by replacing various residues with histidine. Catalysis by wild-type HCA III and these six variants was determined from the initial velocity of hydration of CO2 measured by stopped-flow spectrophotometry and from the exchange of 18O between CO2 and H2O at chemical equilibrium by mass spectrometry. The results show that histidine at three positions (Lys64His, Arg67His and Phe131His) have the capacity to transfer protons during catalysis, enhancing maximal velocity of CO2 hydration and 18O exchange from 4- to 15-fold compared with wild-type HCA III. Histidine residues at the other three positions (Trp5His, Tyr7His, Phe20His) showed no firm evidence for proton transfer. These results are discussed in terms of the stereochemistry of the active-site cavity and possible proton transfer pathways.
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Affiliation(s)
- Haiqian An
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
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37
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Smith KS, Ingram-Smith C, Ferry JG. Roles of the conserved aspartate and arginine in the catalytic mechanism of an archaeal beta-class carbonic anhydrase. J Bacteriol 2002; 184:4240-5. [PMID: 12107142 PMCID: PMC135220 DOI: 10.1128/jb.184.15.4240-4245.2002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The roles of an aspartate and an arginine, which are completely conserved in the active sites of beta-class carbonic anhydrases, were investigated by steady-state kinetic analyses of replacement variants of the beta-class enzyme (Cab) from the archaeon Methanobacterium thermoautotrophicum. Previous kinetic analyses of wild-type Cab indicated a two-step zinc-hydroxide mechanism of catalysis in which the k(cat)/K(m) value depends only on the rate constants for the CO(2) hydration step, whereas k(cat) also depends on rate constants from the proton transfer step (K. S. Smith, N. J. Cosper, C. Stalhandske, R. A. Scott, and J. G. Ferry, J. Bacteriol. 182:6605-6613, 2000). The recently solved crystal structure of Cab shows the presence of a buffer molecule within hydrogen bonding distance of Asp-34, implying a role for this residue in the proton transport step (P. Strop, K. S. Smith, T. M. Iverson, J. G. Ferry, and D. C. Rees, J. Biol. Chem. 276:10299-10305, 2001). The k(cat)/K(m) values of Asp-34 variants were decreased relative to those of the wild type, although not to an extent which supports an essential role for this residue in the CO(2) hydration step. Parallel decreases in k(cat) and k(cat)/K(m) values for the variants precluded any conclusions regarding a role for Asp-34 in the proton transfer step; however, the k(cat) of the D34A variant was chemically rescued by replacement of 2-(N-morpholino)propanesulfonic acid buffer with imidazole at pH 7.2, supporting a role for the conserved aspartate in the proton transfer step. The crystal structure of Cab also shows Arg-36 with two hydrogen bonds to Asp-34. Arg-36 variants had both k(cat) and k(cat)/K(m) values that were decreased at least 250-fold relative to those of the wild type, establishing an essential function for this residue. Imidazole was unable to rescue the k(cat) of the R36A variant; however, partial rescue of the kinetic parameter was obtained with guanidine-HCl indicating that the guanido group of this residue is important.
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Affiliation(s)
- Kerry S Smith
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Schmitt W, Anson CE, Sessoli R, van Veen M, Powell AK. Biomimetic hydrolytic activation by Fe(III) aggregates: structures, reactivity and properties of novel oxo-bridged iron complexes. J Inorg Biochem 2002; 91:173-89. [PMID: 12121774 DOI: 10.1016/s0162-0134(02)00404-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The tetranuclear aggregate (enH(2))[Fe(4)(mu(3)-O)(heidi)(4)(mu-O,O'-O(2)CNHC(2)H(4)NH(3))] x 4H(2)O contains a novel bidentate zwitterionic carbamic acid ligand. Magnetic studies indicate that the unsymmetrical Fe(4) core is ferrimagnetic with an S=4 ground state. Similar ligands have been obtained on rectangular tetranuclear aggregates [M(4)(mu-O)(mu-OH)(hpdta)(2)(mu-X)(2)](n-) (M[double bond]Fe, Al, Ga). The carbamic acid ligands are considered to result from the hydrolytic activation (fixation) of atmospheric CO(2) by the aggregate precursor to give a carbonato intermediate, which then reacts with the organic diamine used as base in the synthesis. Similar aggregates with acetate ligands result from hydrolytic activation of the DMA used as cosolvent. Closely related mechanisms for these two activation processes are proposed, which are also related to the accepted mechanisms for carbonic anhydrase and urease.
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Affiliation(s)
- Wolfgang Schmitt
- Institute for Inorganic Chemistry, University of Karlsruhe, Engesserstrasse Geb. 30.45, D-76128 Karlsruhe, Germany
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Schmitt W, Jordan PA, Henderson RK, Moore GR, Anson CE, Powell AK. Synthesis, structures and properties of hydrolytic Al(III) aggregates and Fe(III) analogues formed with iminodiacetate-based chelating ligands. Coord Chem Rev 2002. [DOI: 10.1016/s0010-8545(02)00110-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Ferraroni M, Tilli S, Briganti F, Chegwidden WR, Supuran CT, Wiebauer KE, Tashian RE, Scozzafava A. Crystal structure of a zinc-activated variant of human carbonic anhydrase I, CA I Michigan 1: evidence for a second zinc binding site involving arginine coordination. Biochemistry 2002; 41:6237-44. [PMID: 12009884 DOI: 10.1021/bi0120446] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The human genetic variant carbonic anhydrase I (CA I) Michigan 1 results from a single point mutation that changes His 67 to Arg in a critical region of the active site. This variant of the zinc metalloenzyme appears to be unique in that it possesses an esterase activity that is specifically enhanced by added free zinc ions. We have determined the three-dimensional structure of human CA I Michigan 1 by X-ray crystallography to a resolution of 2.6 A. In the absence of added zinc ions, the mutated residue, Arg 67, points out of the active site, hydrogen bonding with the carboxylate of Asn 69. This contrasts with the orientation of His 67, in the native isozyme, which points into the active site. The orientations of His 94, His 96, and His 119, that coordinate the catalytic zinc ion, and of the catalytically critical Thr 199-Glu 106 hydrogen bonding system, are largely unchanged in the mutant. The structure of an enzyme adduct with a second zinc bound was determined to a resolution of 2.0 A. The second zinc ion is coordinated to His 64, His 200, and Arg 67. This arginine residue reverses its orientation on zinc binding and turns into the active site. The residues at these three positions have been implicated in determining the specific kinetic properties of native CA I. This is, to our knowledge, the first example of a zinc ion coordinating with an arginine residue in a Zn(II) enzyme.
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Affiliation(s)
- Marta Ferraroni
- Dipartimento di Chimica, Laboratorio di Chimica Bioinorganica, Università degli Studi di Firenze, Via della Lastruccia, 5, I-50019 Sesto Fiorentino, Italy
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41
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Winzor DJ, Carrington LE, Harding SE. Analysis of thermodynamic non-ideality in terms of protein solvation. Biophys Chem 2001; 93:231-40. [PMID: 11804728 DOI: 10.1016/s0301-4622(01)00223-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The effects of thermodynamic non-ideality on the forms of sedimentation equilibrium distributions for several isoelectric proteins have been analysed on the statistical-mechanical basis of excluded volume to obtain an estimate of the extent of protein solvation. Values of the effective solvation parameter delta are reported for ellipsoidal as well as spherical models of the proteins, taken to be rigid, impenetrable macromolecular structures. The dependence of the effective solvated radius upon protein molecular mass exhibits reasonable agreement with the relationship calculated for a model in which the unsolvated protein molecule is surrounded by a 0.52-nm solvation shell. Although the observation that this shell thickness corresponds to a double layer of water molecules may be of questionable relevance to mechanistic interpretation of protein hydration, it augurs well for the assignment of magnitudes to the second virial coefficients of putative complexes in the quantitative characterization of protein-protein interactions under conditions where effects of thermodynamic non-ideality cannot justifiably be neglected.
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Affiliation(s)
- D J Winzor
- Department of Biochemistry, University of Queensland, Brisbane, Queensland 4072, Australia.
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Chazalette C, Riviere-Baudet M, Scozzafava A, Abbate F, Ben Maarouf Z, Supuran CT. Carbonic anhydrase inhibitors, interaction of boron derivatives with isozymes I and II: a new binding site for hydrophobic inhibitors at the entrance of the active site as shown by docking studies. JOURNAL OF ENZYME INHIBITION 2001; 16:125-33. [PMID: 11342281 DOI: 10.1080/14756360109162362] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The interaction of human carbonic anhydrase (hCA) isozymes I and II with boron derivatives was investigated by kinetic and spectroscopic studies. These derivatives, tested as new inhibitors of carbonic anhydrase, are sulfonamide and non-sulfonamide boron derivatives and some of them proved to be moderately efficient inhibitors of hCA I and hCA II, their activities being comparable to those of the unsubstituted sulfonamides, the classical inhibitors of these zinc enzymes. Ph(2) BOH, one of the compounds with the highest affinity for hCA II in the present study, has been docked within the active site. After minimisation it was found situated at 7.9 A from zinc, within the hydrophobic half of the active site, in Van der Waals contacts with the amino acid residues: Val 121, Phe 130, Val 135, Leu 141, Val 143, Val 207 and Pro 201. This is the first time that a CA inhibitor has been found to bind at the edge of the active site cavity, similarly to the CA activator histamine, which binds on the hydrophilic half. This finding may be of importance also for the design of novel types of inhibitors with increased affinity for the different CA isozymes.
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Affiliation(s)
- C Chazalette
- Université Paul Sabatier, Laboratoire d'Hétérochimie Fondamentale et Appliquée, UMR 5069 du CNRS, 118 route de Narbonne, 31062 Toulouse Cedex, France
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Affiliation(s)
- C T Supuran
- Università degli Studi, Laboratorio di Chimica Inorganica e Bioinorganica, Via Gino Capponi 7, 50121 Firenze, Italy
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Affiliation(s)
- S Lindskog
- Department of Biochemistry, Umeå University, S-90187 Umeå, Sweden
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45
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Stams T, Christianson DW. X-ray crystallographic studies of mammalian carbonic anhydrase isozymes. EXS 2001:159-74. [PMID: 11268515 DOI: 10.1007/978-3-0348-8446-4_9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- T Stams
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
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Strop P, Smith KS, Iverson TM, Ferry JG, Rees DC. Crystal structure of the "cab"-type beta class carbonic anhydrase from the archaeon Methanobacterium thermoautotrophicum. J Biol Chem 2001; 276:10299-305. [PMID: 11096105 DOI: 10.1074/jbc.m009182200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structure of the "cab"-type beta class carbonic anhydrase from the archaeon Methanobacterium thermoautotrophicum (Cab) has been determined to 2.1-A resolution using the multiwavelength anomalous diffraction phasing technique. Cab exists as a dimer with a subunit fold similar to that observed in "plant"-type beta class carbonic anhydrases. The active site zinc is coordinated by protein ligands Cys(32), His(87), and Cys(90), with the tetrahedral coordination completed by a water molecule. The major difference between plant- and cab-type beta class carbonic anhydrases is in the organization of the hydrophobic pocket. The structure reveals a Hepes buffer molecule bound 8 A away from the active site zinc, which suggests a possible proton transfer pathway from the active site to the solvent.
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Affiliation(s)
- P Strop
- Biochemistry Option, California Institute of Technology, Pasadena, California 91125, USA
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Smith KS, Cosper NJ, Stalhandske C, Scott RA, Ferry JG. Structural and kinetic characterization of an archaeal beta-class carbonic anhydrase. J Bacteriol 2000; 182:6605-13. [PMID: 11073902 PMCID: PMC111400 DOI: 10.1128/jb.182.23.6605-6613.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The beta-class carbonic anhydrase from the archaeon Methanobacterium thermoautotrophicum (Cab) was structurally and kinetically characterized. Analytical ultracentrifugation experiments show that Cab is a tetramer. Circular dichroism studies of Cab and the Spinacia oleracea (spinach) beta-class carbonic anhydrase indicate that the secondary structure of the beta-class enzymes is predominantly alpha-helical, unlike that of the alpha- or gamma-class enzymes. Extended X-ray absorption fine structure results indicate the active zinc site of Cab is coordinated by two sulfur and two O/N ligands, with the possibility that one of the O/N ligands is derived from histidine and the other from water. Both the steady-state parameters k(cat) and k(cat)/K(m) for CO(2) hydration are pH dependent. The steady-state parameter k(cat) is buffer-dependent in a saturable manner at both pH 8.5 and 6.5, and the analysis suggested a ping-pong mechanism in which buffer is the second substrate. At saturating buffer conditions and pH 8.5, k(cat) is 2.1-fold higher in H(2)O than in D(2)O, consistent with an intramolecular proton transfer step being rate contributing. The steady-state parameter k(cat)/K(m) is not dependent on buffer, and no solvent hydrogen isotope effect was observed. The results suggest a zinc hydroxide mechanism for Cab. The overall results indicate that prokaryotic beta-class carbonic anhydrases have fundamental characteristics similar to the eukaryotic beta-class enzymes and firmly establish that the alpha-, beta-, and gamma-classes are convergently evolved enzymes that, although structurally distinct, are functionally equivalent.
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Affiliation(s)
- K S Smith
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Mallis RJ, Poland BW, Chatterjee TK, Fisher RA, Darmawan S, Honzatko RB, Thomas JA. Crystal structure of S-glutathiolated carbonic anhydrase III. FEBS Lett 2000; 482:237-41. [PMID: 11024467 DOI: 10.1016/s0014-5793(00)02022-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
S-Glutathiolation of carbonic anhydrase III (CAIII) occurs rapidly in hepatocytes under oxidative stress. The crystal structure of the S-glutathiolated CAIII from rat liver reveals covalent adducts on cysteines 183 and 188. Electrostatic charge and steric contacts at each modification site inversely correlate with the relative rates of reactivity of these cysteines toward glutathione (GSH). Diffuse electron density associated with the GSH adducts suggests a lack of preferred bonding interactions between CAIII and the glutathionyl moieties. Hence, the GSH adducts are available for binding by a protein capable of reducing this mixed disulfide. These properties are consistent with the participation of CAIII in the protection/recovery from the damaging effects of oxidative agents.
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Affiliation(s)
- R J Mallis
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
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49
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Abstract
Carbonic anhydrases catalyze the reversible hydration of CO(2) [CO(2)+H(2)Oright harpoon over left harpoon HCO(3)(-)+H(+)]. Since the discovery of this zinc (Zn) metalloenzyme in erythrocytes over 65 years ago, carbonic anhydrase has not only been found in virtually all mammalian tissues but is also abundant in plants and green unicellular algae. The enzyme is important to many eukaryotic physiological processes such as respiration, CO(2) transport and photosynthesis. Although ubiquitous in highly evolved organisms from the Eukarya domain, the enzyme has received scant attention in prokaryotes from the Bacteria and Archaea domains and has been purified from only five species since it was first identified in Neisseria sicca in 1963. Recent work has shown that carbonic anhydrase is widespread in metabolically diverse species from both the Archaea and Bacteria domains indicating that the enzyme has a more extensive and fundamental role in prokaryotic biology than previously recognized. A remarkable feature of carbonic anhydrase is the existence of three distinct classes (designated alpha, beta and gamma) that have no significant sequence identity and were invented independently. Thus, the carbonic anhydrase classes are excellent examples of convergent evolution of catalytic function. Genes encoding enzymes from all three classes have been identified in the prokaryotes with the beta and gamma classes predominating. All of the mammalian isozymes (including the 10 human isozymes) belong to the alpha class; however, only nine alpha class carbonic anhydrase genes have thus far been found in the Bacteria domain and none in the Archaea domain. The beta class is comprised of enzymes from the chloroplasts of both monocotyledonous and dicotyledonous plants as well as enzymes from phylogenetically diverse species from the Archaea and Bacteria domains. The only gamma class carbonic anhydrase that has thus far been isolated and characterized is from the methanoarchaeon Methanosarcina thermophila. Interestingly, many prokaryotes contain carbonic anhydrase genes from more than one class; some even contain genes from all three known classes. In addition, some prokaryotes contain multiple genes encoding carbonic anhydrases from the same class. The presence of multiple carbonic anhydrase genes within a species underscores the importance of this enzyme in prokaryotic physiology; however, the role(s) of this enzyme is still largely unknown. Even though most of the information known about the function(s) of carbonic anhydrase primarily relates to its role in cyanobacterial CO(2) fixation, the prokaryotic enzyme has also been shown to function in cyanate degradation and the survival of intracellular pathogens within their host. Investigations into prokaryotic carbonic anhydrase have already led to the identification of a new class (gamma) and future research will undoubtedly reveal novel functions for carbonic anhydrase in prokaryotes.
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Affiliation(s)
- K S Smith
- Department of Biochemistry and Molecular Biology, 204 South Frear Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
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50
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Kim G, Selengut J, Levine RL. Carbonic anhydrase III: the phosphatase activity is extrinsic. Arch Biochem Biophys 2000; 377:334-40. [PMID: 10845711 DOI: 10.1006/abbi.2000.1793] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The carbonic anhydrases reversibly hydrate carbon dioxide to yield bicarbonate and hydrogen ion. They have a variety of physiological functions, although the specific roles of each of the 10 known isozymes are unclear. Carbonic anhydrase isozyme III is particularly rich in skeletal muscle and adipocytes, and it is unique among the isozymes in also exhibiting phosphatase activity. Previously published studies provided evidence that the phosphatase activity was intrinsic to carbonic anhydrase III, that it had specificity for tyrosine phosphate, and that activity was regulated by reversible glutathionylation of cysteine186. To study the mechanism of this phosphatase, we cloned and expressed the rat liver carbonic anhydrase III. The purified recombinant had the same specific activity as the carbonic anhydrase purified from rat liver, but it had virtually no phosphatase activity. We attempted to identify an activator of the phosphatase in rat liver and found a protein of approximately 14 kDa, the amount of which correlated with the phosphatase activity of the carbonic anhydrase III fractions. It was identified as liver fatty acid binding protein, which was then purified to test for activity as an activator of the phosphatase and for protein-protein interaction, but neither binding nor activation could be demonstrated. Immunoprecipitation experiments established that carbonic anhydrase III could be separated from the phosphatase activity. Finally, adding additional purification steps completely separated the phosphatase activity from the carbonic anhydrase activity. We conclude that the phosphatase activity previously considered to be intrinsic to carbonic anhydrase III is actually extrinsic. Thus, this isozyme exhibits only the carbon dioxide hydratase and esterase activities characteristic of the other mammalian isozymes, and the phosphatase previously shown to be activated by glutathionylation is not carbonic anhydrase III.
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Affiliation(s)
- G Kim
- Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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