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Solvent as a competitive inhibitor for Candida antarctica lipase B
Univ La Rochelle, Lab Biotechnol & Chim Bioorgan.
Univ La Rochelle, Lab Biotechnol & Chim Bioorgan.
Univ La Rochelle, Lab Biotechnol & Chim Bioorgan.
Univ La Rochelle, Lab Biotechnol & Chim Bioorgan.
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2007 (English)In: Biochimica et Biophysica Acta - Proteins and Proteomics, ISSN 1570-9639, E-ISSN 1878-1454, Vol. 1774, no 8, 1052-1057 p.Article in journal (Refereed) Published
Abstract [en]

In enzyme-catalyzed reactions, the choice of solvent often has a marked effect on the reaction outcome. In this paper, it is shown that solvent effects could be explained by the ability of the solvent to act as a competitive inhibitor to the substrate. Experimentally, the effect of six solvents, 2-pentanone, 3-pentanone, 2-methyl-2-pentanol, 3-methyl-3-pentanot, 2-methylpentane and 3-methylpentane, was studied in a solid/gas reactor. As a model reaction, the CALB-catalyzed transacylation between methyl propanoate and I -propanol, was studied. It was shown that both ketones inhibited the enzyme activity whereas the tertiary alcohols and the hydrocarbons did not. Alcohol inhibition constants, K-il were changed to "K-i", determined in presence of 2-pentanone, 3-pentanone, and 3-methyl-3-pentanol, confirmed the marked inhibitory character of the ketones and an absence of inhibition of 3-methyl-3-pentanol. The molecular modeling study was performed on three solvents, 2-pentanone, 2-methyl-2-pentanol and 2-methyl pentane. It showed a clear inhibitory effect for the ketone and the tertiary alcohol, but no effect for the hydrocarbon. No change in enzyme conformation was seen during the simulations. The study led to the conclusion that the effect of added organic component on lipase catalyzed transacylation could be explained by the competitive inhibitory character of solvents towards the first binding substrate methyl propanoate.

Place, publisher, year, edition, pages
2007. Vol. 1774, no 8, 1052-1057 p.
Keyword [en]
kinetics, organic solvent, molecular modeling, solid/gas biocatalysis, conformational change, solubility
National Category
Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kth:diva-14179DOI: 10.1016/j.bbapap.2007.05.013ISI: 000249149600012Scopus ID: 2-s2.0-34547544566OAI: oai:DiVA.org:kth-14179DiVA: diva2:331462
Note
QC 20100722Available from: 2010-07-22 Created: 2010-07-22 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Enzyme substrate solvent interactions: a case study on serine hydrolases
Open this publication in new window or tab >>Enzyme substrate solvent interactions: a case study on serine hydrolases
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Reaction rates and selectivities were measured for transacylation of fatty acid esters in solvents catalysed by Candida antarctica lipase B and by cutinase from Humicola insolens. With these enzymes classical water-based enzymology can be expanded to many different solvents allowing large variations in interaction energies between the enzymes, the substrates and the surrounding. Further ,hydrolysis reactions catalysed by Bacillus subtilis esterase 2 were investigated.

Thermodynamics analyses revealed that the enzyme contribution to reaction rate acceleration compared to acid catalysis was purely entropic. On the other hand, studies of differences in activation entropy and enthalpy between enantiomers and between homologous esters showed that high substrate specificity was favoured by enthalpic stabilisation.

Solvent was found to have a profound effect on enzyme catalysis, affecting both reaction rate and selectivity. Differences in substrate solubility will impact enzyme specificity since substrate binding is an equilibrium between enzyme-bound substrate and substrate in free solution. In addition, solven tmolecules were found to act as enzyme inhibitors, showing both competitive and non-competitive behaviour.

In several homologous data series enthalpy-entropy compensation relationships were encountered. A possible extrathermodynamic relationship between enthalpy and entropy can easily be lost under co-varying errors propagated from the experiments. From the data in this thesis, one instance was found of a real enthalpy-entropy compensation that could be distinguished from statistical errors, while other examples could not be verified.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 43 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2008:15
Keyword
lipase, esterase, specificity
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-4867 (URN)978-91-7415-094-0 (ISBN)
Public defence
2008-09-05, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100722Available from: 2008-09-10 Created: 2008-09-05 Last updated: 2011-07-07Bibliographically approved

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