EFFECTS OF AMPHIPHILES ON TRYPSIN ACTIVITY AND CONFORMATION

Abstract

Amphiphiles with different head groups (sulphate, carboxylate, pyridinium, ammonium, trimethylammonium and oxyethylene) and chain lengths (octyl, dodecyl and hexadecyl) were used to study the effect of amphiphiles on trypsin esterolytic activity, stability and conformation. The electrophoretic mobility of self-digested trypsin samples was used complementarily with activity measurements to follow the deactivation of trypsin. It is concluded that the amphiphile-trypsin interaction is highly dependent on the hydrophilic moiety but also to some extent on the hydrocarbon chain length. Anionic amphiphiles exhibit a stronger influence on trypsin conformation than cationics. With the exception of potassium dodecanoate, the examined anionic surfactants decrease trypsin activity, while both activity and stability of trypsin were increased by the cationic ones. These effects are correlated to conformational changes of the protein, as measured by circular dichroism.