Specificity and essential groups in Alhagain

Abstract

A systematic investigation has been made to determine the relationship between the proteolytic activity and the reactive groups of alhagain. The effects of certain oxidising, reducing, -SH group blocking agents, metal chelating agents, metallic ions and certain other specific agents on the reactive groups and the proteolytic activity of the enzyme have been studied. The results show that -SH group of the enzyme may be essential for its activity. The specificity of alhagain has been studied by quantitatively estimating the free amino acids, N- and C- terminal amino acids of the peptides liberated from hydrolysis of B-chain of oxidised insulin for 6 hours. With reference to the known structure of the B-chain, the major sites of action of alhagain have been determined. Results indicate that alhagain preferentially attacks peptide bonds involving the amino or carboxyl groups of phenyl alanine, amino groups of alanine and serine and also carboxyl groups of lysine and glycine.