Specific cleavages of arginyl peptide bonds at basic amino acid pairs by a serine proteinase from the microsomal membranes of rat liver

Abstract

The specificity of action of a serine proteinase from the microsomal membranes of rat liver was investigated at pH 7.5 and 37°C using various peptides as substrates. HPLC analyses of the peptides produced followed by their amino acid analyses have revealed that the enzyme is a unique endopeptidase specifically cleaving arginyl peptide bonds at paired basic amino acid residues. Thus, the enzyme is suggested to be a kind of processing proteinase involved in the conversion of proproteins to their mature forms. Indeed, the enzyme cleaved specifically the NH 2-terminal 20-residue peptide of proalbumin at the Arg-Arg sequence.