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Comparison of the Binding of Reversible Inhibitors to Human Butyrylcholinesterase and Acetylcholinesterase: A Crystallographic, Kinetic and Calorimetric Study. Molecules 2017; 22:molecules22122098. [PMID: 29186056 PMCID: PMC6149722 DOI: 10.3390/molecules22122098] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/26/2017] [Accepted: 11/27/2017] [Indexed: 12/17/2022] Open
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) hydrolyze the neurotransmitter acetylcholine and, thereby, function as coregulators of cholinergic neurotransmission. Although closely related, these enzymes display very different substrate specificities that only partially overlap. This disparity is largely due to differences in the number of aromatic residues lining the active site gorge, which leads to large differences in the shape of the gorge and potentially to distinct interactions with an individual ligand. Considerable structural information is available for the binding of a wide diversity of ligands to AChE. In contrast, structural data on the binding of reversible ligands to BChE are lacking. In a recent effort, an inhibitor competition approach was used to probe the overlap of ligand binding sites in BChE. Here, we extend this study by solving the crystal structures of human BChE in complex with five reversible ligands, namely, decamethonium, thioflavin T, propidium, huprine, and ethopropazine. We compare these structures to equivalent AChE complexes when available in the protein data bank and supplement this comparison with kinetic data and observations from isothermal titration calorimetry. This new information now allows us to define the binding mode of various ligand families and will be of importance in designing specific reversible ligands of BChE that behave as inhibitors or reactivators.
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Karanth S, Pope C. In Vitro Inhibition of Blood Cholinesterase Activities From Horse, Cow, and Rat by Tetrachlorvinphos. Int J Toxicol 2016; 22:429-33. [PMID: 14680990 DOI: 10.1177/109158180302200604] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The organophosphorus insecticide tetrachlorvinphos (TCVP) is commonly used as a feed-through larvicide in many livestock species, including cattle and horses. Cholinesterase (Ch E) activity in blood (generally plasma or whole blood) is often employed to assess organophosphorus insecticide intoxication in animals as well as humans. In many species, including horse and man, plasma contains predominantly butyrylcholinesterase whereas red blood cells in all species express exclusively acetylcholinesterase. To evalulate the comparative interaction of TCVP with blood Ch Es in different species, we compared the in vitro sensitivity of Ch E activity in plasma and erythrocytes from horse, cow, and rat. Horse plasma Ch E was most sensitive (IC50, 30 minutes, 30°C = 97 n M), whereas horse erythrocyte Ch E activity was least sensitive (IC50 > 1 m M). In contrast, cow plasma Ch E showed lower sensitivity (IC50 = 784 μM) to inhibition by TCVP than erythrocyte Ch E (IC50 = 216 μM). Rat plasma and erythrocyte Ch E activities had relatively similar sensitivity to TCVP (IC50 = 54 μM and 78 μM, respectively). The results suggest that plasma and erythrocyte Ch E from horse, cow, and rat show marked species- and blood fraction-dependent differences in sensitivity to TCVP. Knowledge of such differences in sensitivity of blood Ch E activities to TCVP may be important in the clinical interpretation of intoxication with this pesticide across species.
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Affiliation(s)
- Subramanya Karanth
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
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Park SJ, Lee HW, Kim HR, Kang C, Kim HM. A carboxylesterase-selective ratiometric fluorescent two-photon probe and its application to hepatocytes and liver tissues. Chem Sci 2016; 7:3703-3709. [PMID: 30008999 PMCID: PMC6008934 DOI: 10.1039/c5sc05001d] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 02/23/2016] [Indexed: 12/17/2022] Open
Abstract
Carboxylesterases (CEs) are widely distributed enzymes in the human body that catalyze hydrolysis of various endogenous and exogenous substrates. They are directly linked to hepatic drug metabolisms and steatosis, and their regulations are important issues in pharmacological and clinical applications. In this work, we have developed an emission ratiometric two-photon probe (SE1) for quantitatively detecting CE in situ. This probe is based on a translation of intramolecular charge transfer character upon reaction with CE. It shows a sensitive blue-to-yellow emission change in response to human CE activity, easy loading into cells, insensitivity to pH and other metabolites including ROS and RNS, high photostability, and low cytotoxicity. Using live hepatocytes and liver tissues, we found that ratiometric two-photon microscopic imaging with SE1 is an effective tool for monitoring CE activities at the subcellular level in live tissues. This probe will find useful applications in biomedical research, including studies of hepatic steatosis and drug developments.
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Affiliation(s)
- Sang Jun Park
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Hyo Won Lee
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Hye-Ri Kim
- School of East-West Medical Science , Kyung Hee University , Yongin 446-701 , Korea .
| | - Chulhun Kang
- School of East-West Medical Science , Kyung Hee University , Yongin 446-701 , Korea .
| | - Hwan Myung Kim
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
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Maraković N, Knežević A, Vinković V, Kovarik Z, Šinko G. Design and synthesis of N-substituted-2-hydroxyiminoacetamides and interactions with cholinesterases. Chem Biol Interact 2016; 259:122-132. [PMID: 27238725 DOI: 10.1016/j.cbi.2016.05.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 04/20/2016] [Accepted: 05/25/2016] [Indexed: 11/27/2022]
Abstract
Within this study, we designed and synthesized four new oxime compounds of the N-substituted 2-hydroxyiminoacetamide structure and evaluated their interactions with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Our aim was to explore the possibility of extending the dual-binding mode of interaction between the enzyme and the inhibitor to a so-called triple-binding mode of interaction through the introduction of an additional binding moiety. N-substituted 2-hydroxyiminoacetamide 1 was prepared via BOP catalyzed amidation of hydroxyiminoacetic acid with 3-azido-1-phenylpropylamine. An azide group enabled us to prepare more elaborate structures 2-4 by the copper-catalyzed azide-alkyne cycloaddition. The new compounds 1-4 differed in their presumed AChE peripheral site binding moiety, which ranged from an azide group to functionalized heterocycles. Molecular docking studies revealed that all three binding moieties are involved in the non-covalent interactions with ChEs for all of the four compounds, albeit not always in the complete accordance with the proposed hypothesis. All of the four compounds reversibly inhibited the ChEs with their inhibition potency increasing in the same order for both enzymes (1 < 2 < 4 < 3). A higher preference for binding to BChE (KI from 0.30 μmol/L to 130 μmol/L) over AChE (KI from 50 μmol/L to 1200 μmol/L) was observed for all of the compounds. Compounds were screened for reactivation of cyclosarin-, sarin- and VX-inhibited AChE and BChE.
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Affiliation(s)
- Nikola Maraković
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia
| | | | - Vladimir Vinković
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10 000 Zagreb, Croatia
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia.
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Šinko G, Kovarik Z, Reiner E, Simeon-Rudolf V, Stojan J. Mechanism of stereoselective interaction between butyrylcholinesterase and ethopropazine enantiomers. Biochimie 2011; 93:1797-807. [DOI: 10.1016/j.biochi.2011.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 06/17/2011] [Indexed: 10/18/2022]
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Abstract
Kolinesteraze: struktura, uloga, inhibicijaAcetilkolinesteraza (AChE; E.C. 3.1.1.7) i butirilkolinesteraza (BChE; E.C. 3.1.1.8) enzimi su koji se zbog svoje uloge u organizmu intenzivno istražuju unutar područja biomedicine i toksikologije. Iako strukturno homologni, ovi enzimi razlikuju se prema katalitičkoj aktivnosti, odnosno specifičnosti prema supstratima koje mogu hidrolizirati te selektivnosti za vezanje mnogih liganada. U ovom radu dan je pregled dosadašnjih istraživanja kolinesteraza i njihovih interakcija s ligandima i inhibitorima te su izdvojene aminokiseline aktivnog mjesta koje sudjeluju u tim interakcijama.
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Bosak A, Gazić I, Vinković V, Kovarik Z. Stereoselective inhibition of human, mouse, and horse cholinesterases by bambuterol enantiomers. Chem Biol Interact 2008; 175:192-5. [DOI: 10.1016/j.cbi.2008.04.050] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 04/28/2008] [Accepted: 04/29/2008] [Indexed: 11/30/2022]
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Yücel YY, Tacal O, Ozer I. Comparative effects of cationic triarylmethane, phenoxazine and phenothiazine dyes on horse serum butyrylcholinesterase. Arch Biochem Biophys 2008; 478:201-5. [PMID: 18656440 DOI: 10.1016/j.abb.2008.07.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 07/03/2008] [Accepted: 07/08/2008] [Indexed: 11/18/2022]
Abstract
The kinetic effects of a selection of triarylmethane, phenoxazine and phenothiazine dyes (pararosaniline (PR), malachite green (MG), methyl green (MeG); meldola blue (MB), nile blue (NB), nile red (NR); methylene blue (MethB)) and of ethopropazine on horse serum butyrylcholinesterase were studied spectrophotometrically at 25( degrees )C in 50mM MOPS buffer, pH 8, using butyrylthiocholine as substrate. PR, MeG, MB and ethopropazine acted as linear mixed type inhibitors of the enzyme, with respective K(i) values of 4.5+/-0.50 microM, 0.41+/-0.007 microM, 0.44+/-0.086 microM and 0.050+/-0.0074 microM. MG, NB, MethB and NR caused complex, nonlinear inhibition pointing to cooperative binding at two sites. Intrinsic K' values ( identical with[I](2)(0.5) extrapolated to [S]=0) for MG, NB, NR and MethB were 0.20+/-0.096 microM, 0.0018+/-0.0015 microM, 0.92+/-0.23 microM and 0.23+/-0.08 microM. NB stood out as a potent inhibitor effective at nM levels. Comparison of inhibitory effects on horse and human serum butyrylcholinesterases suggested that the two enzymes must have distinct microstructural features.
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Affiliation(s)
- Yasemin Yücel Yücel
- Department of Biochemistry, School of Pharmacy, Hacettepe University, 06100 Ankara, Turkey
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Knaak JB, Dary CC, Okino MS, Power FW, Zhang X, Thompson CB, Tornero-Velez R, Blancato JN. Parameters for Carbamate Pesticide QSAR and PBPK/PD Models for Human Risk Assessment. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2008; 193:53-212. [PMID: 20614344 DOI: 10.1007/978-0-387-73163-6_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 04/21/2007] [Indexed: 05/29/2023]
Abstract
Our interest in providing parameters for the development of quantitative structure physiologically based pharmacokinetic/pharmacodynamic (QSPBPK/PD) models for assessing health risks to carbamates (USEPA 2005) comes from earlier work with organophosphorus (OP) insecticides (Knaak et al. 2004). Parameters specific to each carbamate are needed in the construction of PBPK/PD models along with their metabolic pathways. Parameters may be obtained by (1) development of QSAR models, (2) collecting pharmacokinetic data, and (3) determining pharmacokinetic parameters by fitting to experimental data. The biological parameters are given in Table 1 (Blancato et al. 2000). Table 1 Biological Parameters Required for Carbamate Pesticide Physiologically Based Pharmacokinetic/Pharmacodynamic (PBPK/PD) Models.(a).
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Affiliation(s)
- James B Knaak
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, SUNY at Buffalo, 3435 Main Street, Buffalo, NY, 14214, USA
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Sinko G, Calić M, Bosak A, Kovarik Z. Limitation of the Ellman method: cholinesterase activity measurement in the presence of oximes. Anal Biochem 2007; 370:223-7. [PMID: 17716616 DOI: 10.1016/j.ab.2007.07.023] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 06/14/2007] [Accepted: 07/16/2007] [Indexed: 11/28/2022]
Abstract
The Ellman method for assaying thiols is widely used for cholinesterase activity measurement. Cholinesterase activity is measured indirectly by quantifying the concentration of 5-thio-2-nitrobenzoic acid (TNB) ion formed in the reaction between the thiol reagent 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) and thiocholine, a product of substrate (i.e., acetylthiocholine [ATCh]) hydrolysis by the cholinesterase. Oximes, reactivators of inhibited cholinesterase, are nucleophiles that also react with ATCh (oximolysis), producing thiocholine and (indirectly) TNB ion. The aim of this study was to characterize ATCh oximolysis. Therefore, we measured the oximolysis between oximes (K027 and HI-6) and ATCh in the presence of DTNB at different pH values, taking into account the final concentration of a product that is thiocholine. To confirm oximate ion involvement in the nucleophilic attack, we also determined the reaction rate between the oximes and ATCh, without DTNB, at different pH values by measuring the decrease in oximate ion absorption over time. The oximate ion of K027 reacted 14 times faster with ATCh (306M(-1)min(-1)) than the oximate ion of HI-6 (22M(-1)min(-1)). However, the rate constants obtained with the Ellman method were 84M(-1)min(-1) for K027 and 22M(-1)min(-1) for HI-6. Our results confirmed that the rate obtained with K027 using the Ellman method is actually the rate of the Ellman reaction itself. This suggests that the Ellman method cannot be used uncritically to evaluate oxime reaction with choline esters, in particular when oximolysis is faster than the Ellman reaction itself at a given pH.
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Affiliation(s)
- Goran Sinko
- Institute for Medical Research and Occupational Health, HR-10001 Zagreb, Croatia.
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Debord J, Verneuil B, Bollinger JC, Merle L, Dantoine T. Flow microcalorimetric study of butyrylcholinesterase kinetics and inhibition. Anal Biochem 2006; 354:299-304. [PMID: 16725100 DOI: 10.1016/j.ab.2006.04.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 04/21/2006] [Accepted: 04/21/2006] [Indexed: 11/17/2022]
Abstract
The enzymatic hydrolysis of butyrylcholine, catalyzed by horse serum butyrylcholinesterase (EC 3.1.1.8), was studied at 37 degrees C in Tris buffer (pH 7.5) by flow microcalorimetry. A convolution procedure, using the Gamma distribution to represent the impulse response of the calorimeter, was developed to analyze the microcalorimetric curves. After correction for buffer protonation, the hydrolysis reaction was found to be slightly endothermic, with Delta H=+9.8 kJ mol(-1). Enzyme kinetics was studied with both the differential and integrated forms of the Michaelis equation with equivalent results: Michaelis constant K(m)=3.3mM, catalytic constant k(cat)=1.7 x 10(3)s(-1), bimolecular rate constant k(s)=5.1 x 10(5)M(-1)s(-1). The reaction product, choline, was found to be a competitive inhibitor with a dissociation constant K(i)=9.1mM. Betaine had a slightly higher affinity for the enzyme, but the inhibition was only partial. This study confirms the usefulness of microcalorimetry for the kinetic study of enzymes and their inhibitors.
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Affiliation(s)
- Jean Debord
- Service de Pharmacologie-Toxicologie, Hôpital Dupuytren, 87042 Limoges, France.
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Sinko G, Calić M, Kovarik Z. para- andortho-Pyridinium aldoximes in reaction with acetylthiocholine. FEBS Lett 2006; 580:3167-72. [PMID: 16684539 DOI: 10.1016/j.febslet.2006.04.070] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 04/24/2006] [Accepted: 04/25/2006] [Indexed: 11/17/2022]
Abstract
In the oximolysis reaction para-aldoximes K027 and TMB-4 react faster with ATCh than ortho-aldoximes HI-6 and K033. The reaction rate constants at 25 degrees C were 22 M(-1) min(-1) for HI-6 and K033, 230 M(-1) min(-1) for TMB-4 and 306 M(-1) min(-1) for K027. Semi-empirical calculations showed that differences in rates do not origin from different electron density on the oxygen of the oxime group, but can be explained by the steric hindrance of the oxime group within the molecule. Thermodynamic parameters, DeltaG#, DeltaH# and DeltaS#, were also determined for oximolysis reaction.
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Affiliation(s)
- Goran Sinko
- Institute for Medical Research and Occupational Health, POB 291, HR-10 001 Zagreb, Croatia
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Küçükkilinç T, Ozer I. Inhibition of human plasma cholinesterase by malachite green and related triarylmethane dyes: Mechanistic implications. Arch Biochem Biophys 2005; 440:118-22. [PMID: 16036213 DOI: 10.1016/j.abb.2005.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 06/07/2005] [Accepted: 06/09/2005] [Indexed: 10/25/2022]
Abstract
The inhibitory effects of the cationic triarylmethane (TAM+) dyes, pararosaniline (PR+), malachite green (MG+), and methyl green (MeG+) on human plasma cholinesterase (BChE) were studied at 25 degrees C in 100 mM Mops, pH 8.0, with butyrylthiocholine as substrate. PR+ and MG+ caused linear mixed inhibition of enzyme activity. The respective inhibitory parameters were K(i) = 1.9 +/- 0.23 microM, alpha = 13 +/- 48, beta = 0 and K(i) = 0.28 +/- 0.037 microM, alpha = 23 +/- 7.4, beta = 0. MeG+ acted as a competitive inhibitor with K(i) = 0.12 +/- 0.017 microM (alpha, infinity, beta, not applicable). The K(i) values were within the same range reported for a number of ChE inhibitors including propidium ion, donepezil, and the phenothiazines, suggesting that TAM+s are active site ligands. On the other hand, the alpha values failed to correlate with values previously reported for a number of ChE inhibitors. It appears that mixed inhibition is the combined result of more than one type of binding and S-I interference. The impact of ligands at the choline-specific and peripheral anionic sites (or, possibly, accessory structural domains) on BChE activity needs to be studied in further detail.
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Affiliation(s)
- Tuba Küçükkilinç
- Department of Biochemistry, School of Pharmacy, Hacettepe University, 06100 Ankara, Turkey
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Stojan J, Golicnik M, Fournier D. Rational polynomial equation as an unbiased approach for the kinetic studies of Drosophila melanogaster acetylcholinesterase reaction mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1703:53-61. [PMID: 15588702 DOI: 10.1016/j.bbapap.2004.09.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 09/01/2004] [Accepted: 09/20/2004] [Indexed: 10/26/2022]
Abstract
The hydrolysis of substrates by cholinesterases does not follow the Michaelis-Menten reaction mechanism. The well-known inhibition by excess substrate is often accompanied by an unexpectedly high activity at low substrate concentrations. It appears that these peculiarities are the consequence of an unusual architecture of the active site, which conducts the substrate molecule over many stages before it is cleaved and released. Structural and kinetic data also suggest that two substrate molecules can attach at the same time to the free, as well as to the acetylated, enzyme. We present a procedure which provides an unbiased framework for mathematical modelling of such complex reaction mechanisms. It is based on regression analysis of a rational polynomial using classical initial rate data. The determination of polynomial degree reveals the number of independent parameters that can be evaluated from the available information. Once determined, these parameters can substantially facilitate the construction and evaluation of a kinetic model reflecting the expected molecular events in an enzymic reaction. We also present practical suggestions for testing the postulated kinetic model, using an original thermodynamic approach and an isolated effect in a specifically mutated enzyme.
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Affiliation(s)
- Jure Stojan
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia.
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