Comparative effects of alcohols (methanol, glycerol) and polyethylene glycol (PEG-300) on acid denatured state of goat liver cystatin

Abstract

This report summarizes the effect of methanol, glycerol and polyol (PEG) on the acid induced state of goat liver cystatin by various spectroscopic techniques. Native goat liver cystatin (LC) has a fluorescence maximum at 340 nm, whereas the acid induced state shows a red shift of 15 nm with enhanced fluorescence intensity. Addition of 80% (V/V) methanol and glycerol both were found to stabilise the acid induced state of goat liver cystatin. However, glycerol was found to be a better stabilising agent than methanol. The unfolded state of liver cystatin obtained at pH 2 underwent a series of conformational changes when exposed to PEG-300 at varying concentrations. Tertiary structure was stabilized only at low concentrations of PEG-300 but higher concentrations resulted in the loss of tertiary structure.