No abstract

No abstract

The effect of interaction between proteins and amphiphiles on the surface tension reduction have been measured by the drop-volume method. The equilibrium surface tension reduction isotherms at the air/water interface of serum albumin and of ovalbumin in sodium dodecylsulphate and of ovalbumin in l-monocaproin are reported. The surface tension reduction isotherms of the proteins in the anionic amphiphile solutions exhibit plateau regions, which have been interpreted in terms of different states of protein-amphiphile interaction in the bulk solution. Any interaction between ovalbumin and the monoglyceride is not reflected in the surface tension isotherm. At increased amphiphile concentration the protein seems to be replaced by 1-monocaproin in the surface.

Amphi philes with different head groups (sul phate, carboxylate, pyridinium, ammonium, trimethylammonium and oxyethylene) and chain 1engths (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 hydrophil i c moi ety 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 stabi 1i ty of tryps i n were increased by the cati onicones. These effects are correlated to conformational changes of the protein, as measured by circular dichroism.

No abstract