Do organic solvents affect the catalytic properties of lipase? Intrinsic kinetic parameters of lipases in ester hydrolysis and formation in various organic solvents

Journal Article · Wed Jul 05 04:00:00 EDT 1995 · Biotechnology and Bioengineering

OSTI ID:78136

Tol, J B.A. van; Stevens, R M.M.; Veldhuizen, W J; Jongejan, J A; Duine, J A ^[1]

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1. Delft Univ. of Technology (Netherlands)

When it is assumed that organic solvents do not interfere with the binding process nor with the catalytic mechanism, the contribution of substrate-solvent interactions to enzyme kinetics can be accounted for by just replacing substrate concentrations in the equations by thermodynamic activities. It appears from the transformation that only the affinity parameters (K{sub m},k{sub sp}) are affected by this. Thus, in theory, the values of these corrected, intrinsic parameters (K{sub m}{sup int}, k{sub sp}{sup int}) and the maximal rate (V{sub 1}) should be equal for all media. This was tested for hydrolysis, transesterification, and esterification reactions catalyzed by pig pancreas lipase and Pseudomonas cepacia lipase in various organic solvents. Correction was carried out via experimentally determined activity coefficients for the substrates in these solvents or, if not feasible, from values in data bases. However, although the kinetic performances of each enzyme in the solvents became much more similar after correction, differences still remained. Analysis of the enzyme suspensions revealed massive particles, which explains the low activity of enzymes in organic solvents. However, no correlation was found between estimates of the amount of catalytically available enzyme (present at the surface of suspended particles or immobilized on beads) and the maximal rates observed. Moreover, the solvents had similar effects on the intrinsic parameters of suspended and immobilized enzyme. The possible causes for the effects of the solvents on the catalytic performance of the enzymes, remaining after correction for solvent-substrate interactions and the amount of participating enzyme, are discussed with respect to the premises on which the correction method is based.

• OSTI ID: 78136
• Journal Information: Biotechnology and Bioengineering, Journal Name: Biotechnology and Bioengineering Journal Issue: 1 Vol. 47; ISSN BIBIAU; ISSN 0006-3592
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL EFFECTS
ENZYMATIC HYDROLYSIS
ENZYME ACTIVITY
ESTERS
LIPASES
MATHEMATICAL MODELS
ORGANIC SOLVENTS