A three‐dimensional solubility parameter approach to nonaqueous enzymology

Abstract

Widespread commercial application of enzymes as catalysts for specialty or commodity chemical synthesis will require their use in nonaqueous systems. While a number of non-aqueous enzyme applications have been demonstrated, the lack of useful rules for predicting enzyme-solvent interactions has hindered the development of this technology. Both Hildebrand and solvent hydrophobicity (octanol-water partition coefficient) parameters have been used previously to correlate and predict enzyme activity in nonaqueous systems, with some success, but any single-parameter approach is inherently limited in its ability to reflect the spectrum of possible enzyme-solvent interactions. Therefore, this study evaluates the three-dimensional solubility parameter space, as proposed by Hansen, to correlate and predict enzyme activity in microaqueous, miscible, and biphasic nonaqueous systems. Preliminary results suggest that Hansen parameters may be useful for correlating nonaqueous enzyme activity, and that the dispersive and polar parameters may be disproportionately important in single-phase microaqueous systems. The Hansen hydrogen-bonding parameter appears to be the only parameter yet evaluated capable of correlating the water requirement for enzyme activity in microaqueous systems, suggesting that water affects protein structure through enthalpic rather than entropic processes in nonaqueous systems. Insufficient data are available for miscible and biphasic systems, but it is proposed that enzyme activity may correlate with the average solubility parameters of miscible systems and of the aqueous phase in biphasic systems.

Solvent polarity influences product selectivity of lipase‐mediated esterification reactions in microaqueous media

“…One factor important to microaqueous biocatalysis in general is phase behavior of reaction media, where it is often considered that single-liquid phases (viz., homogeneous catalysis) are gene.rally more benign to enzymes (because of less interfacial inactivation) and pose less restraints on masstransfer or diffusional processes than do multiple-liquid phase systems (heterogeneous catalysis) (2,39). We found little evidence to suggest that either single-or multiple-liquid phase mixtures were more efficient for the lipase reactions studied here.…”

Study of phytoproteases stability in aqueous-organic biphasic systems using linear free energy relationships

“…Several authors have attempted to correlate and predict enzyme activity and/or stability in non-aqueous systems with certain solvent parameters such as dielectric constant, water solubility, Hildebrand solubility, three-dimensional solubility parameter space and log P oct . In practice, however, log P oct values are still used as a good guidance for the purpose of solvent selection for biocatalysis [11,[37][38][39]. Nevertheless, in this case, there is no straightforward correlation between log P oct values and the behavior of some phytoproteases in the aqueous-organic biphasic systems under study.…”

“…An approach to understand the catalytic activity of enzymes in organic solvents is to use the socalled linear free energy relationships (LFERs) to describe quantitatively the solvents effects on enzymatic catalysis [9]. Thus, several solvent physical properties such as hydrophobicity measured as the octanol-water partition coefficient (commonly used in its logarithmic form), dielectric constant and dipole moment have all been used to predict the catalytic activity of enzymes [10][11][12]. However, the predictive power of such one-parameter LFERs is quite limited because not always a single-parameter is able to describe appropriately all the enzyme-solvent interactions to allow a quantitative description of the solvent effects on biocatalytic activity [13].…”

Aplicações sintéticas de lipases imobilizadas em polímeros

“…Parâmetros como constante dielétrica (ε) 54,55 , polarizabilidade 57 , bem como o parâmetro de solubilidade de Hildebrand (δ) 58 e o de solubilidade tridimensional 59 -uma derivação do parâmetro de Hildebrand -são propostos para verificar a influência do solvente nas reações catalisadas por enzimas imobilizadas ou não.…”