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Yildirim-Elikoglu S, Erdem YK. Interactions between milk proteins and polyphenols: Binding mechanisms, related changes, and the future trends in the dairy industry. FOOD REVIEWS INTERNATIONAL 2017. [DOI: 10.1080/87559129.2017.1377225] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Seda Yildirim-Elikoglu
- Department of Food Engineering, Faculty of Engineering, Hacettepe University, Ankara, Turkey
| | - Yasar Kemal Erdem
- Department of Food Engineering, Faculty of Engineering, Hacettepe University, Ankara, Turkey
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2
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Sauer J, Abou Hachem M, Svensson B, Jensen KJ, Thygesen MB. Kinetic analysis of inhibition of glucoamylase and active site mutants via chemoselective oxime immobilization of acarbose on SPR chip surfaces. Carbohydr Res 2013; 375:21-8. [PMID: 23680647 DOI: 10.1016/j.carres.2013.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 10/26/2022]
Abstract
We here report a quantitative study on the binding kinetics of inhibition of the enzyme glucoamylase and how individual active site amino acid mutations influence kinetics. To address this challenge, we have developed a fast and efficient method for anchoring native acarbose to gold chip surfaces for surface plasmon resonance studies employing wild type glucoamylase and active site mutants, Y175F, E180Q, and R54L, as analytes. The key method was the chemoselective and protecting group-free oxime functionalization of the pseudo-tetrasaccharide-based inhibitor acarbose. By using this technique we have shown that at pH 7.0 the association and dissociation rate constants for the acarbose-glucoamylase interaction are 10(4)M(-1)s(-1) and 10(3)s(-1), respectively, and that the conformational change to a tight enzyme-inhibitor complex affects the dissociation rate constant by a factor of 10(2)s(-1). Additionally, the acarbose-presenting SPR surfaces could be used as a glucoamylase sensor that allowed rapid, label-free affinity screening of small carbohydrate-based inhibitors in solution, which is otherwise difficult with immobilized enzymes or other proteins.
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Affiliation(s)
- Jørgen Sauer
- Centre for Carbohydrate Recognition and Signalling, Department of Chemistry, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark
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3
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Bonfig KB, Gabler A, Simon UK, Luschin-Ebengreuth N, Hatz M, Berger S, Muhammad N, Zeier J, Sinha AK, Roitsch T. Post-translational derepression of invertase activity in source leaves via down-regulation of invertase inhibitor expression is part of the plant defense response. MOLECULAR PLANT 2010; 3:1037-48. [PMID: 20833735 DOI: 10.1093/mp/ssq053] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
There is increasing evidence that pathogens do not only elicit direct defense responses, but also cause pronounced changes in primary carbohydrate metabolism. Cell-wall-bound invertases belong to the key regulators of carbohydrate partitioning and source-sink relations. Whereas studies have focused so far only on the transcriptional induction of invertase genes in response to pathogen infection, the role of post-translational regulation of invertase activity has been neglected and was the focus of the present study. Expression analyses revealed that the high mRNA level of one out of three proteinaceous invertase inhibitors in source leaves of Arabidopsis thaliana is strongly repressed upon infection by a virulent strain of Pseudomonas syringae pv. tomato DC3000. This repression is paralleled by a decrease in invertase inhibitor activity. The physiological role of this regulatory mechanism is revealed by the finding that in situ invertase activity was detectable only upon infection by P. syringae. In contrast, a high invertase activity could be measured in vitro in crude and cell wall extracts prepared from both infected and non-infected leaves. The discrepancy between the in situ and in vitro invertase activity of control leaves and the high in situ invertase activity in infected leaves can be explained by the pathogen-dependent repression of invertase inhibitor expression and a concomitant reduction in invertase inhibitor activity. The functional importance of the release of invertase from post-translational inhibition for the defense response was substantiated by the application of the competitive chemical invertase inhibitor acarbose. Post-translational inhibition of extracellular invertase activity by infiltration of acarbose in leaves was shown to increase the susceptibility to P. syringae. The impact of invertase inhibition on spatial and temporal dynamics of the repression of photosynthesis and promotion of bacterial growth during pathogen infection supports a role for extracellular invertase in plant defense. The acarbose-mediated increase in susceptibility was also detectable in sid2 and cpr6 mutants and resulted in slightly elevated levels of salicylic acid, demonstrating that the effect is independent of the salicylic acid-regulated defense pathway. These findings provide an explanation for high extractable invertase activity found in source leaves that is kept inhibited in situ by post-translational interaction between invertase and the invertase inhibitor proteins. Upon pathogen infection, the invertase activity is released by repression of invertase inhibitor expression, thus linking the local induction of sink strength to the plant defense response.
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Affiliation(s)
- Katharina B Bonfig
- Julius-von-Sachs-Institut fuer Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universitaet Wuerzburg, Julius-von-Sachs-Platz 2, 97082 Wuerzburg, Germany
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4
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Johnson GP, Petersen L, French AD, Reilly PJ. Twisting of glycosidic bonds by hydrolases. Carbohydr Res 2009; 344:2157-66. [PMID: 19733839 DOI: 10.1016/j.carres.2009.08.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 08/07/2009] [Accepted: 08/11/2009] [Indexed: 11/30/2022]
Abstract
Patterns of scissile bond twisting have been found in crystal structures of glycoside hydrolases (GHs) that are complexed with substrates and inhibitors. To estimate the increased potential energy in the substrates that results from this twisting, we have plotted torsion angles for the scissile bonds on hybrid Quantum Mechanics::Molecular Mechanics energy surfaces. Eight such maps were constructed, including one for alpha-maltose and three for different forms of methyl alpha-acarviosinide to provide energies for twisting of alpha-(1,4) glycosidic bonds. Maps were also made for beta-thiocellobiose and for three beta-cellobiose conformers having different glycon ring shapes to model distortions of beta-(1,4) glycosidic bonds. Different GH families twist scissile glycosidic bonds differently, increasing their potential energies from 0.5 to 9.5 kcal/mol. In general, the direction of twisting of the glycosidic bond away from the conformation of lowest intramolecular energy correlates with the position (syn or anti) of the proton donor with respect to the glycon's ring oxygen atom. This correlation suggests that glycosidic bond distortion is important for the optimal orientation of one of the glycosidic oxygen lone pairs toward the enzyme's proton donor.
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Affiliation(s)
- Glenn P Johnson
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70124-4305, USA
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5
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Perozzo R, Folkers G, Scapozza L. Thermodynamics of Protein–Ligand Interactions: History, Presence, and Future Aspects. J Recept Signal Transduct Res 2009; 24:1-52. [PMID: 15344878 DOI: 10.1081/rrs-120037896] [Citation(s) in RCA: 266] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The understanding of molecular recognition processes of small ligands and biological macromolecules requires a complete characterization of the binding energetics and correlation of thermodynamic data with interacting structures involved. A quantitative description of the forces that govern molecular associations requires determination of changes of all thermodynamic parameters, including free energy of binding (deltaG), enthalpy (deltaH), and entropy (deltaS) of binding and the heat capacity change (deltaCp). A close insight into the binding process is of significant and practical interest, since it provides the fundamental know-how for development of structure-based molecular design-strategies. The only direct method to measure the heat change during complex formation at constant temperature is provided by isothermal titration calorimetry (ITC). With this method one binding partner is titrated into a solution containing the interaction partner, thereby generating or absorbing heat. This heat is the direct observable that can be quantified by the calorimeter. The use of ITC has been limited due to the lack of sensitivity, but recent developments in instrument design permit to measure heat effects generated by nanomol (typically 10-100) amounts of reactants. ITC has emerged as the primary tool for characterizing interactions in terms of thermodynamic parameters. Because heat changes occur in almost all chemical and biochemical processes, ITC can be used for numerous applications, e.g., binding studies of antibody-antigen, protein-peptide, protein-protein, enzyme-inhibitor or enzyme-substrate, carbohydrate-protein, DNA-protein (and many more) interactions as well as enzyme kinetics. Under appropriate conditions data analysis from a single experiment yields deltaH, K(B), the stoichiometry (n), deltaG and deltaS of binding. Moreover, ITC experiments performed at different temperatures yield the heat capacity change (deltaCp). The informational content of thermodynamic data is large, and it has been shown that it plays an important role in the elucidation of binding mechanisms and, through the link to structural data, also in rational drug design. In this review we will present a comprehensive overview to ITC by giving some historical background to calorimetry, outline some critical experimental and data analysis aspects, discuss the latest developments, and give three recent examples of studies published with respect to macromolecule-ligand interactions that have utilized ITC technology.
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Affiliation(s)
- Remo Perozzo
- Department of Chemistry and Applied BioSciences, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
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6
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Henzl MT. Chapter 10 Characterization of Parvalbumin and Polcalcin Divalent Ion Binding by Isothermal Titration Calorimetry. Methods Enzymol 2009; 455:259-97. [DOI: 10.1016/s0076-6879(08)04210-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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7
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Isoperibolic Titration Calorimetry as a Tool for the Prediction of Thermodynamic Properties of Cyclodextrins. ENERGIES 2008. [DOI: 10.3390/en1030093] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Tan TC, Mijts BN, Swaminathan K, Patel BK, Divne C. Crystal Structure of the Polyextremophilic α-Amylase AmyB from Halothermothrix orenii: Details of a Productive Enzyme–Substrate Complex and an N Domain with a Role in Binding Raw Starch. J Mol Biol 2008; 378:852-70. [DOI: 10.1016/j.jmb.2008.02.041] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 02/15/2008] [Accepted: 02/19/2008] [Indexed: 11/15/2022]
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9
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Götmar G, Samuelsson J, Karlsson A, Fornstedt T. Thermodynamic characterization of the adsorption of selected chiral compounds on immobilized amyloglucosidase in liquid chromatography. J Chromatogr A 2007; 1156:3-13. [PMID: 17240382 DOI: 10.1016/j.chroma.2006.12.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 12/18/2006] [Accepted: 12/20/2006] [Indexed: 11/26/2022]
Abstract
Immobilized amyloglucosidase was used as a chiral stationary phase (CSP). First, the retention and enantioselectivity of several model chiral amines and acids were investigated. We found that this CSP was unable to separate the enantiomers of acids, though all selected amines could be resolved. The adsorption of (R)- and (S)-propranolol and its influence on column temperature and 2-propanol content in the eluent were then studied in detail, using a three-step methodology. The adsorption was first evaluated using Scatchard plots; thereafter, the adsorption was characterized in detail by calculating the adsorption energy distribution. With this model-independent information, a better judgment could be made of the possible adsorption models selected in the last step, the model fitting to the data. In the case examined, the bi-Langmuir model (containing nonselective and enantioselective sites) describes the system well. The retention of (R)- and (S)-propranolol at low temperatures increases with the content of 2-propanol in the eluent, due to the increased saturation capacity of the enantioselective sites. The retention is an enthalpy-driven process at both types of sites, whereas the enantioseparation is due to differences between the entropy changes of the two enantiomers at the enantioselective sites. The enthalpy of adsorption at the nonselective sites is almost identical at the two concentrations of 2-propanol in the eluent. Enantioselective adsorption, on the other hand, is more exothermic at higher modifier content (20%). Thus, at high temperatures the retention decreases with increasing modifier content, whereas the opposite (unusual) trend is the case at low temperatures.
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Affiliation(s)
- Gustaf Götmar
- Department of Physical and Analytical Chemistry, Uppsala, Sweden
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Scaffidi A, Stubbs KA, Dennis RJ, Taylor EJ, Davies GJ, Vocadlo DJ, Stick RV. A 1-acetamido derivative of 6-epi-valienamine: an inhibitor of a diverse group of β-N-acetylglucosaminidases. Org Biomol Chem 2007; 5:3013-9. [PMID: 17728868 DOI: 10.1039/b709681j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of an analogue of 6-epi-valienamine bearing an acetamido group and its characterisation as an inhibitor of beta-N-acetylglucosaminidases are described. The compound is a good inhibitor of both human O-GlcNAcase and human beta-hexosaminidase, as well as two bacterial beta-N-acetylglucosaminidases. A 3-D structure of the complex of Bacteroides thetaiotaomicron BtGH84 with the inhibitor shows the unsaturated ring is surprisingly distorted away from its favoured solution phase conformation and reveals potential for improved inhibitor potency.
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Affiliation(s)
- Adrian Scaffidi
- Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, Australia
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11
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Darling RJ, Brault PA. Kinetic exclusion assay technology: characterization of molecular interactions. Assay Drug Dev Technol 2005; 2:647-57. [PMID: 15674023 DOI: 10.1089/adt.2004.2.647] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Characterization of intermolecular interactions in terms of affinity, binding kinetics, stoichiometry, specificity, and thermodynamics can facilitate the selection of lead compounds in the discovery and development of protein therapeutics. KinExA (Sapidyne Instruments, Inc., Boise, ID) is a relatively new technology that is gaining use in characterizing molecular interactions, particularly with respect to antibody therapeutics. KinExA offers a platform that allows the measurement of true equilibrium binding affinity and kinetics using unmodified molecules in solution phase. This is accomplished by using a solid-phase immobilized molecule to probe for free concentration of one interaction component after allowing sufficient time to reach equilibrium (affinity measurements), or under pre-equilibrium conditions (kinetics). In this review, the theory behind KinExA technology is discussed, and examples of applying this technology to antibody characterization are provided. Finally, a comparison among KinExA, Biacore (surface plasmon resonance), and isothermal titration calorimetry is presented, and potential future improvements and applications of KinExA are discussed.
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Affiliation(s)
- Ryan J Darling
- BioTechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285, USA.
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Lepre CA, Moore JM, Peng JW. Theory and applications of NMR-based screening in pharmaceutical research. Chem Rev 2004; 104:3641-76. [PMID: 15303832 DOI: 10.1021/cr030409h] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher A Lepre
- Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, MA 02139-4242, USA
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Létoffé S, Debarbieux L, Izadi N, Delepelaire P, Wandersman C. Ligand delivery by haem carrier proteins: the binding of Serratia marcescens haemophore to its outer membrane receptor is mediated by two distinct peptide regions. Mol Microbiol 2003; 50:77-88. [PMID: 14507365 DOI: 10.1046/j.1365-2958.2003.03686.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Haem is involved in essential processes. It is toxic and thus is not found free in living organisms but almost entirely sequestered by haem carrier proteins. We investigated the mechanisms of haem transfer between the proteins of a bacterial haem acquisition system involving haemophores. Haemophores are secreted by several Gram-negative bacteria and are able to extract haem (assimilated as an iron source) from haemoproteins and deliver it to specific outer membrane receptors. The Serratia marcescens haemophore (HasA) is folded into a globular form and tyrosine and histidine are involved in haem ligation. Interaction with the receptor is of high affinity (5 nM) and does not involve haem. Identification and study of mutants with altered binding properties led to the description of two regions of the haemophore that bind to the receptor. They consist of residues involved in two beta strands located on the same side of HasA. Each region is sufficient for high affinity binding. The synthetic peptide corresponding to one beta strand competes with the corresponding haemophore region for binding to the receptor, suggesting that the two binding regions are independent binding sites. We propose a model for haem release and transfer to the receptor.
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Affiliation(s)
- Sylvie Létoffé
- Unité des Membranes Bactériennes, Institut Pasteur (CNRS URA2172) 25 rue du Dr Roux, 75724 Paris Cedex 15, France
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Laederach A, Reilly PJ. Specific empirical free energy function for automated docking of carbohydrates to proteins. J Comput Chem 2003; 24:1748-57. [PMID: 12964193 DOI: 10.1002/jcc.10288] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We present an automated docking protocol specifically optimized to predict the structure and affinity of a protein-carbohydrate complex. A scoring function was developed based on a training set of 30 protein-carbohydrate complexes of known structure and affinity. Combinations of several models for hydrogen bonding, torsional entropy loss, and solvation were tested for their ability to fit the training set data, and the best model was used with AutoDock. The electrostatic empirical coefficient is larger than in a previously obtained model using a training set comprised of various types of protein-ligand complexes, indicating that electrostatic interactions play a more important role in determining the affinity between a carbohydrate and a protein. The differences in the relative weighting of the empirical coefficients in the model yields predicted free energies for the training set with a standard error of 1.403 kcal/mol. The new scoring function was tested on 17 Aspergillus niger glucoamylase inhibitors for which binding energies had been determined experimentally. Free energies of complex formation were predicted with a residual standard error of 1.101 kcal/mol. The new scoring function therefore provides a robust method for predicting free energies of formation and optimal conformations of carbohydrate-protein complexes.
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Affiliation(s)
- Alain Laederach
- Department of Chemical Engineering, Iowa State University, 2114 Sweeney Hall, Ames, IA 50011, USA
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Affiliation(s)
- Trine Christensen
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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Henzl MT, Larson JD, Agah S. Estimation of parvalbumin Ca(2+)- and Mg(2+)-binding constants by global least-squares analysis of isothermal titration calorimetry data. Anal Biochem 2003; 319:216-33. [PMID: 12871715 DOI: 10.1016/s0003-2697(03)00288-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The use of competitive isothermal titration calorimetry (ITC) to measure high-affinity binding constants has been largely restricted to systems with a single binding site or multiple identical sites. This study demonstrates the extension of this approach to proteins with two nonequivalent EF-hand Ca(2+)-binding sites--rat beta parvalbumin and the S55D/E59D variant of rat alpha parvalbumin. The method involves simultaneous (global) least-squares analysis of titrations with Ca(2+), with Mg(2+), with Ca(2+) in the presence of Mg(2+), and with Ca(2+) or Mg(2+) in the presence of a competitive chelator (EDTA or EGTA). The Ca(2+) and Mg(2+) binding constants obtained for rat beta agree well with estimates obtained by flow dialysis. Although the Ca(2+) affinity of alpha S55D/E59D is too high to measure by flow dialysis, it was amenable to analysis using the ITC-based approach. The combined S55D and E59D mutations increase the Ca(2+) and Mg(2+) affinities of the mutated binding site by factors of 14 and 26, respectively. This behavior is consistent with that seen previously for the rat beta S55D variant.
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Affiliation(s)
- Michael T Henzl
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO 65211, USA.
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17
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Christensen T, Frandsen TP, Kaarsholm NC, Svensson B, Sigurskjold BW. Physicochemical characterisation of the two active site mutants Trp(52)-->Phe and Asp(55)-->Val of glucoamylase from Aspergillus niger. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1601:163-71. [PMID: 12445478 DOI: 10.1016/s1570-9639(02)00463-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Glucoamylase 1 (GA1) from Aspergillus niger is a multidomain starch hydrolysing enzyme that consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated linker. The fungus also produces a truncated form without the starch-binding domain (GA2). The active site mutant Trp(52)-->Phe of both forms and the Asp(55)-->Val mutant of the GA1 form have been prepared and physicochemically characterised and compared to recombinant wild-type enzymes. The characterisation included substrate hydrolysis, inhibitor binding, denaturant stability, and thermal stability, and the consequences for the active site of glucoamylase are discussed. The circular dichroic (CD) spectra of the mutants were very similar to the wild-type enzymes, indicating that they have similar tertiary structures. The D55V GA1 mutant showed slower kinetics of hydrolysis of maltose and maltoheptaose with delta delta G(double dagger) congruent with 22 kJ mol(-1), whereas the binding of the strong inhibitor acarbose was greatly diminished by delta delta G degrees congruent with 52 kJ mol(-1). Both W52F mutant forms have almost the same stability as the wild-type enzyme, whereas the D55V GA1 mutant showed slight destabilisation both towards denaturant and heat (DSC). The difference between the CD unfolding curves recorded by near- and far-UV indicated that D55V GA1 unfolds through a molten globule intermediate.
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Affiliation(s)
- Trine Christensen
- Department of Biochemistry, August Krogh Institute, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
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Nielsen BR, Lehmbeck J, Frandsen TP. Cloning, heterologous expression, and enzymatic characterization of a thermostable glucoamylase from Talaromyces emersonii. Protein Expr Purif 2002; 26:1-8. [PMID: 12356463 DOI: 10.1016/s1046-5928(02)00505-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The gene encoding a thermostable glucoamylase from Talaromyces emersonii was cloned and, subsequently, heterologously expressed in Aspergillus niger. This glucoamylase gene encodes a 618 amino acid long protein with a calculated molecular weight of 62,827Da. T. emersonii glucoamylase fall into glucoside hydrolase family 15, showing approximately 60% sequence similarity to glucoamylase from A. niger. The expressed enzyme shows high specific activity towards maltose, isomaltose, and maltoheptaose, having 3-6-fold elevated k(cat) compared to A. niger glucoamylase. T. emersonii glucoamylase showed significantly improved thermostability with a half life of 48h at 65 degrees C in 30% (w/v) glucose, compared to 10h for glucoamylase from A. niger. The ability of the glucoamylase to hydrolyse amylopectin at 65 degrees C is improved compared to A. niger glucoamylase, giving a significant higher final glucose yield at elevated temperatures. The increased thermal stability is thus reflected in the industrial performance, allowing T. emersonii glucoamylase to operate at a temperature higher than the A. niger enzyme.
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Affiliation(s)
- Joseph J Lundquist
- Department of Chemistry, Duke University, B120 LSRC, Durham, North Carolina 27708-0317, USA
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Ward WH, Holdgate GA. Isothermal titration calorimetry in drug discovery. PROGRESS IN MEDICINAL CHEMISTRY 2002; 38:309-76. [PMID: 11774798 DOI: 10.1016/s0079-6468(08)70097-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Isothermal titration calorimetry (ITC) follows the heat change when a test compound binds to a target protein. It allows precise measurement of affinity. The method is direct, making interpretation facile, because there is no requirement for competing molecules. Titration in the presence of other ligands rapidly provides information on the mechanism of action of the test compound, identifying the intermolecular complexes that are relevant for structure-based design. Calorimetry allows measurement of stoichiometry and so evaluation of the proportion of the sample that is functional. ITC can characterize protein fragments and catalytically inactive mutant enzymes. It is the only technique which directly measures the enthalpy of binding (delta H degree). Interpretation of delta H degree and its temperature dependence (delta Cp) is usually qualitative, not quantitative. This is because of complicated contributions from linked equilibria and a single change in structure giving modification of several physicochemical properties. Measured delta H degree values allow characterization of proton movement linked to the association of protein and ligand, giving information on the ionization of groups involved in binding. Biochemical systems characteristically exhibit enthalpy-entropy compensation where increased bonding is offset by an entropic penalty, reducing the magnitude of change in affinity. This also causes a lack of correlation between the free energy of binding (delta G degree) and delta H degree. When characterizing structure-activity relationships (SAR), most groups involved in binding can be detected as contributing to delta H degree, but not to affinity. Large enthalpy changes may reflect a modified binding mode, or protein conformation changes. Thus, delta H degree values may highlight a potential discontinuity in SAR, so that experimental structural data are likely to be particularly valuable in molecular design.
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Affiliation(s)
- W H Ward
- AstraZeneca, R & D Mereside, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK
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Peterson KM, Gopalan KV, Nandy A, Srivastava DK. Influence of Glu-376 --> Gln mutation on enthalpy and heat capacity changes for the binding of slightly altered ligands to medium chain acyl-CoA dehydrogenase. Protein Sci 2001; 10:1822-34. [PMID: 11514673 PMCID: PMC2252429 DOI: 10.1110/ps.51401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2000] [Revised: 05/04/2001] [Accepted: 06/07/2001] [Indexed: 10/17/2022]
Abstract
We showed that the alpha-CH(2) --> NH substitution in octanoyl-CoA alters the ground and transition state energies for the binding of the CoA ligands to medium-chain acyl-CoA dehydrogenase (MCAD), and such an effect is caused by a small electrostatic difference between the ligands. To ascertain the extent that the electrostatic contribution of the ligand structure and/or the enzyme site environment modulates the thermodynamics of the enzyme-ligand interaction, we undertook comparative microcalorimetric studies for the binding of 2-azaoctanoyl-CoA (alpha-CH(2) --> NH substituted octanoyl-CoA) and octenoyl-CoA to the wild-type and Glu-376 --> Gln mutant enzymes. The experimental data revealed that both enthalpy (DeltaH degrees ) and heat capacity changes (DeltaC(p) degrees ) for the binding of 2-azaoctanoyl-CoA (DeltaH degrees (298) = -21.7 +/- 0.8 kcal/mole, DeltaC(p) degrees = -0.627 +/- 0.04 kcal/mole/K) to the wild-type MCAD were more negative than those obtained for the binding of octenoyl-CoA (DeltaH degrees (298) = -17.2 +/- 1.6 kcal/mole, DeltaC(p) degrees = -0.526 +/- 0.03 kcal/mole/K). Of these, the decrease in the magnitude of DeltaC(p) degrees for the binding of 2-azaoctanoyl-CoA (vis-à-vis octenoyl-CoA) to the enzyme was unexpected, because the former ligand could be envisaged to be more polar than the latter. To our further surprise, the ligand-dependent discrimination in the above parameters was completely abolished on Glu-376 --> Gln mutation of the enzyme. Both DeltaH degrees and DeltaC(p) degrees values for the binding of 2-azaoctanoyl-CoA (DeltaH degrees (298) = -13.3 +/- 0.6 kcal/mole, DeltaC(p) degrees = -0.511 +/- 0.03 kcal/mole/K) to the E376Q mutant enzyme were found to be correspondingly identical to those obtained for the binding of octenoyl-CoA (DeltaH degrees (298) = -13.2 +/- 0.6 kcal/mole, DeltaC(p) degrees = -0.520 +/- 0.02 kcal/mole/K). However, in neither case could the experimentally determined DeltaC(p) degrees values be predicted on the basis of the changes in the water accessible surface areas of the enzyme and ligand species. Arguments are presented that the origin of the above thermodynamic differences lies in solvent reorganization and water-mediated electrostatic interaction between ligands and enzyme site groups, and such interactions are intrinsic to the molecular basis of the enzyme-ligand complementarity.
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Affiliation(s)
- K M Peterson
- Department of Biochemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota 58105, USA
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23
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Spohr U, Le N, Ling CC, Lemieux RU. The syntheses of 6-C-alkyl derivatives of methyl α-isomaltoside for a study of the mechanism of hydrolysis by amyloglucosidase. CAN J CHEM 2001. [DOI: 10.1139/v01-005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The epimeric (6aR)- and (6aS)-C-alkyl (methyl, ethyl and isopropyl) derivatives of methyl α-isomaltoside (1) were synthesized in order to examine the effects of introducing alkyl groups of increasing bulk on the rate of catalysis for the hydrolysis of the interunit α-glycosidic bond by the enzyme amyloglucosidase, EC 3.2.1.3, commonly termed glucoamylase (AMG). It was previously established that methyl (6aR)-C-methyl α-isomaltoside is hydrolysed about 2 times faster than methyl α-isomaltoside and about 8 times faster than its S-isomer. The kinetics for the hydrolyses of the ethyl and isopropyl analogs were also recently published. As was expected from molecular model calculations, all the R-epimers are good substrates. A rationale is presented for the catalysis based on conventional mechanistic theories that includes the assistance for the decomposition of the activated complex to products by the presence of a hydrogen bond, which connects the 4a-hydroxyl group to the tryptophane and arginine units. It is proposed that activation of the initially formed complex to the transition state is assisted by the energy released as a result of both of the displacement of perturbed water molecules of hydration at the surfaces of both the polyamphiphilic substrate and the combining site and the establishment of intermolecular hydrogen bonds, i.e., micro-thermodynamics. The dissipation of the heat to the bulk solution is impeded by a shell of aromatic amino acids that surround the combining site. Such shields are known to be located around the combining sites of lectins and carbohydrate specific antibodies and are considered necessary to prevent the disruption of the intermolecular hydrogen bonds, which are of key importance for the stability of the complex. These features together with the exquisite stereoelectronic dispositions of the reacting molecules within the combining site offer a rationalization for the catalysis at ambient temperatures and near neutral pH. The syntheses involved the addition of alkyl Grignard reagents to methyl 6-aldehydo-α-D-glucopyranoside. The addition favoured formation of the S-epimers by over 90%. Useful amounts of the active R-isomers were obtained by epimerization of the chiral centers using conventional methods. Glycosylation of the resulting alcohols under conditions for bromide-ion catalysis, provided methyl (6aS)- and (6aR)-C-alkyl-hepta-O-benzyl-α-isomaltosides. Catalytic hydrogenolysis of the benzyl groups afforded the desired disaccharides. 1H NMR studies established the absolute configurations and provided evidence for conformational preferences.Key words: amyloglucosidase (AMG), exo-anomeric effect, 6-C-alkyl-α-D-glucopyranosides and isomaltosides, mechanism of enzyme catalysis.
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24
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Sauer J, Sigurskjold BW, Christensen U, Frandsen TP, Mirgorodskaya E, Harrison M, Roepstorff P, Svensson B. Glucoamylase: structure/function relationships, and protein engineering. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1543:275-293. [PMID: 11150611 DOI: 10.1016/s0167-4838(00)00232-6] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glucoamylases are inverting exo-acting starch hydrolases releasing beta-glucose from the non-reducing ends of starch and related substrates. The majority of glucoamylases are multidomain enzymes consisting of a catalytic domain connected to a starch-binding domain by an O-glycosylated linker region. Three-dimensional structures have been determined of free and inhibitor complexed glucoamylases from Aspergillus awamori var. X100, Aspergillus niger, and Saccharomycopsis fibuligera. The catalytic domain folds as a twisted (alpha/alpha)(6)-barrel with a central funnel-shaped active site, while the starch-binding domain folds as an antiparallel beta-barrel and has two binding sites for starch or beta-cyclodextrin. Certain glucoamylases are widely applied industrially in the manufacture of glucose and fructose syrups. For more than a decade mutational investigations of glucoamylase have addressed fundamental structure/function relationships in the binding and catalytic mechanisms. In parallel, issues of relevance for application have been pursued using protein engineering to improve the industrial properties. The present review focuses on recent findings on the catalytic site, mechanism of action, substrate recognition, the linker region, the multidomain architecture, the engineering of specificity and stability, and roles of individual substrate binding subsites.
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Affiliation(s)
- J Sauer
- Department of Chemistry, Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Copenhagen, Valby, Denmark
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25
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Zhang YL, Yao ZJ, Sarmiento M, Wu L, Burke TR, Zhang ZY. Thermodynamic study of ligand binding to protein-tyrosine phosphatase 1B and its substrate-trapping mutants. J Biol Chem 2000; 275:34205-12. [PMID: 10952978 DOI: 10.1074/jbc.m004490200] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The binding of several phosphonodifluoromethyl phenylalanine (F(2)Pmp)-containing peptides to protein-tyrosine phosphatase 1B (PTP1B) and its substrate-trapping mutants (C215S and D181A) has been studied using isothermal titration calorimetry. The binding of a high affinity ligand, Ac-Asp-Ala-Asp-Glu-F(2)Pmp-Leu-NH(2), to PTP1B (K(d) = 0.24 microm) is favored by both enthalpic and entropic contributions. Disruption of ionic interactions between the side chain of Arg-47 and the N-terminal acidic residues reduces the binding affinity primarily through the reduction of the TDeltaS term. The role of Arg-47 may be to maximize surface contact between PTP1B and the peptide, which contributes to high affinity binding. The active site Cys-215 --> Ser mutant PTP1B binds ligands with the same affinity as the wild-type enzyme. However, unlike wild-type PTP1B, peptide binding to C215S is predominantly driven by enthalpy change, which likely results from the elimination of the electrostatic repulsion between the thiolate anion and the phosphonate group. The increased enthalpic contribution is offset by reduction in the binding entropy, which may be the result of increased entropy of the unbound protein caused by this mutation. The general acid-deficient mutant D181A binds the peptide 5-fold tighter than the C215S mutant, consistent with the observation that the Asp to Ala mutant is a better "substrate-trapping" reagent than C215S. The increased binding affinity for D181A as compared with the wild-type PTP1B results primarily from an increase in the DeltaH of binding in the mutant, which may be related to decreased electrostatic repulsion between the phosphate moiety and PTP1B. These results have important implications for the design of high affinity PTP1B inhibitors.
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Affiliation(s)
- Y L Zhang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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26
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Frandsen TP, Lok F, Mirgorodskaya E, Roepstorff P, Svensson B. Purification, enzymatic characterization, and nucleotide sequence of a high-isoelectric-point alpha-glucosidase from barley malt. PLANT PHYSIOLOGY 2000; 123:275-286. [PMID: 10806244 PMCID: PMC59001 DOI: 10.1104/pp.123.1.275] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/1999] [Accepted: 01/23/2000] [Indexed: 05/23/2023]
Abstract
High-isoelectric-point (pI) alpha-glucosidase was purified 7, 300-fold from an extract of barley (Hordeum vulgare) malt by ammonium sulfate fractionation, ion-exchange, and butyl-Sepharose chromatography. The enzyme had high activity toward maltose (k(cat) = 25 s(-1)), with an optimum at pH 4.5, and catalyzed the hydrolysis by a retaining mechanism, as shown by nuclear magnetic resonance. Acarbose was a strong inhibitor (K(i) = 1.5 microM). Molecular recognition revealed that all OH-groups in the non-reducing ring and OH-3 in the reducing ring of maltose formed important hydrogen bonds to the enzyme in the transition state complex. Mass spectrometry of tryptic fragments assigned the 92-kD protein to a barley cDNA (GenBank accession no. U22450) that appears to encode an alpha-glucosidase. A corresponding sequence (HvAgl97; GenBank accession no. AF118226) was isolated from a genomic phage library using a cDNA fragment from a barley cDNA library. HvAgl97 encodes a putative 96.6-kD protein of 879 amino acids with 93.8% identity to the protein deduced from U22450. The sequence contains two active site motifs of glycoside hydrolase family 31. Three introns of 86 to 4,286 bp interrupt the coding region. The four exons vary from 218 to 1,529 bp. Gene expression analysis showed that transcription reached a maximum 48 h after the start of germination.
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Affiliation(s)
- T P Frandsen
- Department of Chemistry, Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Copenhagen Valby, Denmark
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27
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Weimar T, Petersen BO, Svensson B, Pinto BM. Determination of the solution conformation of d-gluco-dihydroacarbose, a high-affinity inhibitor bound to glucoamylase by transferred NOE NMR spectroscopy. Carbohydr Res 2000; 326:50-5. [PMID: 16001506 DOI: 10.1016/s0008-6215(00)00021-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The determination of the bound solution conformation of D-gluco-dihydroacarbose (GAC), a tight-binding inhibitor of several glycosidase and amylase enzymes, by glucoamylase is described. Transferred NOE NMR experiments and line-broadening effects indicate that GAC is bound in a conformation resembling that observed in the crystal structure. This contrasts with the predominant conformation of GAC when free in solution. The NMR results also suggest regions on the carbohydrate that are in close contact with the protein. The determination of the bound solution conformation of GAC by glucoamylase using transferred NOE (trNOE) measurements is a significant achievement given the high affinity constant (Ka = 3 x 10(7) M(-1)) for this receptor-ligand pair. It is striking that the off-rate for complexation is still sufficiently high to permit observation of trNOEs.
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Affiliation(s)
- T Weimar
- Institut für Chemie, Medizinische Universität zu Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.
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28
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Milne KG, Ferguson MA. Cloning, expression, and characterization of the acyl-CoA-binding protein in African trypanosomes. J Biol Chem 2000; 275:12503-8. [PMID: 10777537 DOI: 10.1074/jbc.275.17.12503] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
African trypanosomes are shielded from their hosts' defenses by a coat of variant surface glycoprotein molecules, each of which is attached to the plasma membrane by a glycosylphosphatidylinositol anchor. During the later stages of glycosylphosphatidylinositol biosynthesis, myristic acid is incorporated into the anchor from the donor myristoyl-CoA by a series of unique fatty acid remodeling and exchange reactions. We have cloned and expressed a recombinant trypanosome acyl-CoA-binding protein that has a preference for binding relatively short chain acyl-CoAs and that has a high affinity for binding myristoyl-CoA (K(d) = 3.5 x 10(-10) M). This protein enhances fatty acid remodeling of glycosylphosphatidylinositol precursors in the trypanosome cell-free system. We speculate that the trypanosome acyl-CoA-binding protein plays an active role in supplying myristoyl-CoA to the fatty acid remodeling machinery in the parasite.
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Affiliation(s)
- K G Milne
- Division of Molecular Parasitology and Biological Chemistry, Department of Biochemistry, The Wellcome Trust Building, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom.
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29
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Sigurskjold BW. Exact analysis of competition ligand binding by displacement isothermal titration calorimetry. Anal Biochem 2000; 277:260-6. [PMID: 10625516 DOI: 10.1006/abio.1999.4402] [Citation(s) in RCA: 269] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rigorous method for the least-squares nonlinear regression analysis of displacement isothermal titration calorimetric data is presented. The method can fit the binding isotherm of a ligand which is competitively inhibited in its binding by another bound ligand to a molecule with n identical and independent binding sites. There are no other assumptions for the method and no approximations. Analysis of previously published data of the strong binding of acarbose to glucoamylase is presented as an example. The regression equations have been programmed for the Origin software supplied with the widely used titration calorimeters from Microcal, Inc., and an Origin Function Definition File with instructions is freely available from the author upon e-mail request.
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Affiliation(s)
- B W Sigurskjold
- Department of Biochemistry, August Krogh Institute, University of Copenhagen, Universitetsparken 13, Copenhagen O, DK-2100, Denmark.
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30
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Randell KD, Frandsen TP, Stoffer B, Johnson MA, Svensson B, Pinto BM. Synthesis and glycosidase inhibitory activity of 5-thioglucopyranosylamines. Molecular modeling of complexes with glucoamylase. Carbohydr Res 1999; 321:143-56. [PMID: 10614065 DOI: 10.1016/s0008-6215(99)00177-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The synthesis of a series of 5-thio-D-glucopyranosylarylamines by reaction of 5-thio-D-glucopyranose pentaacetate with the corresponding arylamine and mercuric chloride catalyst is reported. The products were obtained as anomeric mixtures of the tetraacetates which can be separated and crystallized. The tetraacetates were deprotected to give alpha/beta mixtures of the parent compounds which were evaluated as inhibitors of the hydrolysis of maltose by glucoamylase G2 (GA). A transferred NOE NMR experiment with an alpha/beta mixture of 7 in the presence of GA showed that only the alpha isomer is bound by the enzyme. The Ki values, calculated on the basis of specific binding of the alpha isomers, are 0.47 mM for p-methoxy-N-phenyl-5-thio-D-glucopyranosylamine (7), 0.78 mM for N-phenyl-5-thio-D-glucopyranosylamine (8), 0.27 mM for p-nitro-N-phenyl-5-thio-D-glucopyranosylamine (9) and 0.87 mM for p-trifluoromethyl-N-phenyl-5-thio-D-glucopyranosylamine (10), and the K(m) values for the substrates maltose and p-nitrophenyl alpha-D-glucopyranoside are 1.2 and 3.7 mM, respectively. Methyl 4-amino-4-deoxy-4-N-(5'-thio-alpha-D-glucopyranosyl)-alpha-D-glucopyrano side (11) is a competitive inhibitor of GA wild-type (Ki 4 microM) and the active site mutant Trp120-->Phe GA (Ki 0.12 mM). Compounds 7, 8, and 11 are also competitive inhibitors of alpha-glucosidase from brewer's yeast, with Ki values of 1.05 mM, > 10 mM, and 0.5 mM, respectively. Molecular modeling of the inhibitors in the catalytic site of GA was used to probe the ligand-enzyme complementary interactions and to offer insight into the differences in inhibitory potencies of the ligands.
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Affiliation(s)
- K D Randell
- Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada
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31
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Solovicová A, Christensen T, Hostinová E, Gasperík J, Sevcĭk J, Svensson B. Structure-function relationships in glucoamylases encoded by variant Saccharomycopsis fibuligera genes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:756-64. [PMID: 10491121 DOI: 10.1046/j.1432-1327.1999.00634.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mutation Gly467-->Ser in Glu glucoamylase was designed to investigate differences between two highly homologous wild-type Saccharomycopsis fibuligera Gla and Glu glucoamylases. Gly467, localized in the conserved active site region, S5, is replaced by Ser in the Gla glucoamylase. These amino acid residues are the only two known to occupy this position in the elucidated glucoamylase sequences. The data from the kinetic analysis revealed that replacement of Gly467 with Ser in Glu glucoamylase decreased the kcat towards all substrates tested to values comparable with those of the Gla enzyme. Moreover, the mutant glucoamylase appeared to be less stable compared to the wild-type Glu glucoamylase with respect to thermal unfolding. Microcalorimetric titration studies of the interaction with the inhibitor acarbose indicated differences in the binding between Gla and Glu enzymes. The Gla glucoamylase, although less active, binds acarbose stronger (Ka congruent with 10(13).M(-1)) than the Glu enzyme (Ka congruent with 10(12).M(-1)). In all enzymes studied, the binding of acarbose was clearly driven by enthalpy, with a slightly favorable entropic contribution. The binding of another glucoamylase inhibitor, 1-deoxynojirimycin, was about 8-9 orders of magnitude weaker (Ka congruent with 10(4).M(-1)) than that of acarbose. From comparison of kinetic parameters for the nonglycosylated and glycosylated enzymes it can be deduced that the glycosylation does not play a critical role in enzymatic activity. However, results from differential scanning calorimetry demonstrate an important role of the carbohydrate moiety in the thermal stability of glucoamylase.
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Affiliation(s)
- A Solovicová
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia.
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32
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Jelesarov I, Bosshard HR. Isothermal titration calorimetry and differential scanning calorimetry as complementary tools to investigate the energetics of biomolecular recognition. J Mol Recognit 1999; 12:3-18. [PMID: 10398392 DOI: 10.1002/(sici)1099-1352(199901/02)12:1<3::aid-jmr441>3.0.co;2-6] [Citation(s) in RCA: 537] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The principles of isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) are reviewed together with the basic thermodynamic formalism on which the two techniques are based. Although ITC is particularly suitable to follow the energetics of an association reaction between biomolecules, the combination of ITC and DSC provides a more comprehensive description of the thermodynamics of an associating system. The reason is that the parameters DeltaG, DeltaH, DeltaS, and DeltaCp obtained from ITC are global properties of the system under study. They may be composed to varying degrees of contributions from the binding reaction proper, from conformational changes of the component molecules during association, and from changes in molecule/solvent interactions and in the state of protonation.
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Affiliation(s)
- I Jelesarov
- Department of Biochemistry, University of Zurich, CH-8057 Zurich, Switzerland
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33
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DiRusso CC, Tsvetnitsky V, Højrup P, Knudsen J. Fatty acyl-CoA binding domain of the transcription factor FadR. Characterization by deletion, affinity labeling, and isothermal titration calorimetry. J Biol Chem 1998; 273:33652-9. [PMID: 9837950 DOI: 10.1074/jbc.273.50.33652] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli transcription factor FadR regulates genes required for fatty acid biosynthesis and degradation in an opposing manner. It is acting as an activator of biosynthetic genes and a repressor of degradative genes. The DNA binding of FadR to regions within the promoters of responsive genes and operons is inhibited by long chain acyl-CoA thioesters but not free fatty acids or coenzyme A. The acyl-CoA binding domain of FadR was localized by affinity labeling of the full-length protein and an amino-terminal deletion derivative, FadRDelta1-167, with a palmitoyl-CoA analogue, 9-p-azidophenoxy[9-3H]nonanoic acid-CoA ester. Analysis of labeled peptides generated by tryptic digestion of the affinity-labeled proteins identified one peptide common to both the full-length protein and the deletion derivative. The amino-terminal sequence of the labeled peptide was SLALGFYHK, which corresponds to amino acids 187-195 in FadR. Isothermal titration calorimetry was used to estimate affinity of the wild-type full-length FadR, a His-tagged derivative, and FadRDelta1-167 for acyl-CoA. The binding was characterized by a large negative DeltaH0, -16 to -20 kcal mol-1. No binding was detected for the medium chain ligand C8-CoA. Full-length wild-type FadR and His6-FadR bound oleoyl-CoA and myristoyl-CoA with similar affinities, Kd of 45 and 63 nM and 68 and 59 nM, respectively. The Kd for palmitoyl-CoA binding was about 5-fold higher despite the fact that palmitoyl-CoA is 50-fold more efficient in inhibiting FadR binding to DNA than myristoyl-CoA. The results indicate that both acyl-CoA chain length and the presence of double bonds in the acyl chain affect FadR ligand binding.
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Affiliation(s)
- C C DiRusso
- Department of Biochemistry and Molecular Biology, Albany Medical College, Albany, New York 12208, USA
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34
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André G, Buléon A, Tran V, Vallée F, Juy M, Haser R. Amylose chain behavior in an interacting context I. Influence of a nonchair ring on the maltose conformations. Biopolymers 1998. [DOI: 10.1002/(sici)1097-0282(199611)39:5<737::aid-bip12>3.0.co;2-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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35
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Frandsen TP, Palcic MM, Dupont C, Svensson B. Glucoamylase mutants with decreased Km-values for C-6 substituted isomaltosides. Carbohydr Res 1998. [DOI: 10.1016/s0008-6215(98)00283-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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36
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Zhang YL, Zhang ZY. Low-affinity binding determined by titration calorimetry using a high-affinity coupling ligand: a thermodynamic study of ligand binding to protein tyrosine phosphatase 1B. Anal Biochem 1998; 261:139-48. [PMID: 9716416 DOI: 10.1006/abio.1998.2738] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A competition-based method is used for the determination of the thermodynamic parameters for a low-affinity ligand binding reaction by isothermal titration calorimetry. This method is based on the coupling of a high-affinity ligand to the binding of the low-affinity ligand. Results are presented for the binding of a nonhydrolyzable phosphotyrosine analog phosphonodifluoromethyl phenylalanine (F2Pmp)-containing peptide (Ac-Asp-Ala-Asp-Glu-F2Pmp-Leu-NH2), arsenate, and inorganic phosphate to the intracellular human protein tyrosine phosphatase 1B(PTP1B). The binding constants are 3.3 x 10(6), 4.3 x 10(3), and 48 M-1 for the F2Pmp-containing peptide, arsenate, and inorganic phosphate, respectively. The binding of arsenate and inorganic phosphate to PTP1B is enthalpy driven. This is in contrast to the binding of the F2Pmp-containing peptide which is mainly driven by entropy. The calorimetrically determined binding constants are in agreement with the Ki values determined by enzyme inhibition studies. This demonstrates that isothermal titration calorimetry can be used to quantitatively determine the thermodynamic parameters for the interactions between proteins and low-affinity ligands if a proper coupling ligand can be identified.
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Affiliation(s)
- Y L Zhang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA
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37
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Faergeman NJ, Knudsen J. Role of long-chain fatty acyl-CoA esters in the regulation of metabolism and in cell signalling. Biochem J 1997; 323 ( Pt 1):1-12. [PMID: 9173866 PMCID: PMC1218279 DOI: 10.1042/bj3230001] [Citation(s) in RCA: 530] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The intracellular concentration of free unbound acyl-CoA esters is tightly controlled by feedback inhibition of the acyl-CoA synthetase and is buffered by specific acyl-CoA binding proteins. Excessive increases in the concentration are expected to be prevented by conversion into acylcarnitines or by hydrolysis by acyl-CoA hydrolases. Under normal physiological conditions the free cytosolic concentration of acyl-CoA esters will be in the low nanomolar range, and it is unlikely to exceed 200 nM under the most extreme conditions. The fact that acetyl-CoA carboxylase is active during fatty acid synthesis (Ki for acyl-CoA is 5 nM) indicates strongly that the free cytosolic acyl-CoA concentration is below 5 nM under these conditions. Only a limited number of the reported experiments on the effects of acyl-CoA on cellular functions and enzymes have been carried out at low physiological concentrations in the presence of the appropriate acyl-CoA-buffering binding proteins. Re-evaluation of many of the reported effects is therefore urgently required. However, the observations that the ryanodine-senstitive Ca2+-release channel is regulated by long-chain acyl-CoA esters in the presence of a molar excess of acyl-CoA binding protein and that acetyl-CoA carboxylase, the AMP kinase kinase and the Escherichia coli transcription factor FadR are affected by low nanomolar concentrations of acyl-CoA indicate that long-chain acyl-CoA esters can act as regulatory molecules in vivo. This view is further supported by the observation that fatty acids do not repress expression of acetyl-CoA carboxylase or Delta9-desaturase in yeast deficient in acyl-CoA synthetase.
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Affiliation(s)
- N J Faergeman
- Institute of Biochemistry, Odense University, DK-5230 Odense, Denmark
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Coutinho PM, Dowd MK, Reilly PJ. Automated docking of monosaccharide substrates and analogues and methyl alpha-acarviosinide in the glucoamylase active site. Proteins 1997; 27:235-48. [PMID: 9061788 DOI: 10.1002/(sici)1097-0134(199702)27:2<235::aid-prot10>3.0.co;2-n] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Glucoamylase is an important industrial glucohydrolase with a large specificity range. To investigate its interaction with the monosaccharides D-glucose, D-mannose, and D-galactose and with the substrate analogues 1-deoxynojirimycin, D-glucono-1,5-lactone, and methyl alpha-acarviosinide, MM3(92)-optimized structures were docked into its active site using AutoDock 2.1. The results were compared to structures of glucoamylase complexes obtained by protein crystallography. Charged forms of some substrate analogues were also docked to assess the degree of protonation possessed by glucoamylase inhibitors. Many forms of methyl alpha-acarviosinide were conformationally mapped by using MM3(92), characterizing the conformational pH dependence found for the acarbose family of glucosidase inhibitors. Their significant conformers, representing the most common states of the inhibitor, were used as initial structures for docking. This constitutes a new approach for the exploration of binding modes of carbohydrate chains. Docking results differ slightly from x-ray crystallographic data, the difference being of the order of the crystallographic error. The estimated energetic interactions, even though agreeing in some cases with experimental binding kinetics, are only qualitative due to the large approximations made by AutoDock force field.
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Affiliation(s)
- P M Coutinho
- Department of Chemical Engineering, Iowa State University, Ames, USA
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39
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Ladbury JE, Chowdhry BZ. Sensing the heat: the application of isothermal titration calorimetry to thermodynamic studies of biomolecular interactions. CHEMISTRY & BIOLOGY 1996; 3:791-801. [PMID: 8939696 DOI: 10.1016/s1074-5521(96)90063-0] [Citation(s) in RCA: 233] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Biomolecular interactions can be defined by combining thermodynamic data on the energetic properties of the interaction with high-resolution structural data. The development of high sensitivity isothermal titration calorimetric equipment provides a dramatic advance in the gathering of thermodynamic data, and the interactions between biological macromolecules can now be described with unprecedented accuracy.
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Affiliation(s)
- J E Ladbury
- Department of Biochemistry, University College London, 91 Riding House Street, London W1P 8BT, UK
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40
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Goti A, Cardona F, Brandi A, Picasso S, Vogel P. (1S,2S,7R,8aS)- and (1S,2S,7S,8aS)-trihydroxyoctahydroindolizine: Two new glycosidase inhibitors by nitrone cycloaddition strategy. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0957-4166(96)00200-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
The availability of sensitive calorimetric instrumentation has led to a considerable increase in thermodynamic studies of proteins, nucleic acids, and their interactions. This article reviews some of the recent contributions of calorimetry to characterizing the thermodynamic origins of protein and nucleic acid stability and conformational preferences, as well as the interactions of proteins with each other, with small molecules, and with nucleic acids.
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Affiliation(s)
- G E Plum
- Department of Chemistry, Rutgers, State University of New Jersey, Piscataway 08855, USA
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42
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Stoffer B, Aleshin AE, Firsov LM, Svensson B, Honzatko RB. Refined structure for the complex of D-gluco-dihydroacarbose with glucoamylase from Aspergillus awamori var. X100 to 2.2 A resolution: dual conformations for extended inhibitors bound to the active site of glucoamylase. FEBS Lett 1995; 358:57-61. [PMID: 7821430 DOI: 10.1016/0014-5793(94)01354-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The crystal structure at pH 4 of the complex of glucoamylase II(471) from Aspergillus awamori var. X100 with the pseudotetrasaccharide D-gluco-dihydroacarbose has been refined to an R-factor of 0.125 against data to 2.2 A resolution. The first two residues of the inhibitor bind at a position nearly identical to those of the closely related inhibitor acarbose in its complex with glucoamylase at pH 6. However, the electron density bifurcates beyond the second residue of the D-gluco-dihydroacarbose molecule, placing the third and fourth residues together at two positions in the active site. The position of relatively low density (estimated occupancy of 35%) corresponds to the location of the third and fourth residues of acarbose in its complex with glucoamylase at pH 6. The position of high density (65% occupancy) corresponds to a new binding mode of an extended inhibitor to the active site of glucoamylase. Presented are possible causes for the binding of D-gluco-dihydroacarbose in two conformations at the active site of glucoamylase at pH 4.
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Affiliation(s)
- B Stoffer
- Department of Chemistry, Carlsberg Laboratory, Copenhagen Valby, Denmark
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