Immiscible organic solvent inactivation of urease, chymotrypsin, lipase, and ribonuclease: Separation of dissolved solvent and interfacial effects

Abstract

A new technique with controlled interface generation allows separation and quantitation of enzyme inactivation by both solvent/aqueous interface and dissolved solvent. This has now been used in n-butanol, isopropylether, 2-octanone, n-hexane, n-butylbenzene, and n-tridecane. Ribonuclease was stable with all the solvent/aqueous interfaces studied. Chymotrypsin was mainly inactivated by the more hydrophobic solvent/aqueous interfaces, whereas lipase was only inactivated by the less hydrophobic solvent/aqueous interfaces. Urease was inactivated by some interfaces, but not all, without an obvious trend. Thus, the commonly expected simple relationship with solvent polarity (e.g., log P) does not apply when interfacial inactivation is determined specifically. Greater dissolved solvent inactivation occurred with the more polar solvents, though only a general trend was apparent with log P. A better correlation was noted with the Hilde-brand solubility parameter. Interfacial effects are discussed with reference to enzyme molecular weight, denaturation temperature, hydrophobicity, and adiabatic compressibility.

How do additives affect enzyme activity and stability in nonaqueous media?

“…Inactivation of the protein occurs predominantly at interfaces, e.g. solid/liquid and liquid/liquid, and/or as a result of direct interactions with the solvent (Ghatorae, 1994).…”

Role of pyruvate in enhancing pyruvate decarboxylase stability towards benzaldehyde

“…Inactivation at an organic/aqueous interphase has been reported for several enzyme systems (Ghatorae et al, 1994). (b) Impact of dissolved benzaldehyde such as covalent protein modification or non-covalent interaction.…”

Synthesis of Surfactants Using Enzymes

“…The solvent influences the rate of enzymatic reactions by solvating the substrate with varying efficiency and by direct interaction with the enzyme [9]. Often hydrophobic solvents are less inactivating to enzymes than hydrophilic ones, but several exceptions have been found [10,11]. For use in organic media, the enzymes need to be immobilized to a solid support or cross-linked in order to avoid any protein aggregation [12,13].…”