Stability and activity modulation of chymotrypsins in AOT reversed micelles by protein–interface interaction: Interaction of α-chymotrypsin with a negative interface leads to a cooperative breakage of a salt bridge that keeps the catalytic active conformation (Ile16–Asp194)

Abstract

The stability of α‐chymotrypsin and δ‐chymotrypsin was studied in reversed micelles of sodium bis(2‐ethylhexyl)sulfosuccinate (AOT) in isooctane. α‐Chymotrypsin is inactivated at the interface and at the water pool, while δ‐chymotrypsin is inactivated only at the water pool. The mechanism of inactivation at the interface is related to the interaction of N‐terminal group alanine 149 (absent in δ‐chymotrypsin) with the negative interface. The dependence of enzyme activity on water content of these two enzymes in reversed micelles of AOT is also related with the interface interaction, since δ‐chymotrypsin does not have a bell‐shaped curve as observed for α‐chymotrypsin. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:360–363, 1998.

Overview of the Stability of α-Chymotrypsin in Different Solvent Media

“…The interior part of the CT structure is entirely hydrophobic in nature. These hydrophobic interactions with amino acid residues of CT play an important role in many biological processes and stability results such as membrane and micelle formation, − protein interactions, in addition to protein stability. The hydrophobic interaction is usually assumed to be a force responsible for the low solubility of nonpolar substances in water .…”

Superactivity and conformational changes on alpha-chymotrypsin upon interfacial binding to cationic micelles

“…The activity of many soluble enzymes increases when solubilized in reversed micelles [3,4,[6][7][8][9], where the superactivity usually has a bell-shaped dependence on W 0 . In some cases, the maximum activity is observed when the reversed micelle is slightly bigger than the enzyme [7]. Aqueous micelles can also be used as a biomimetic system.…”