A processing enzyme for prorenin in mouse submandibular gland. Purification and characterization.

Renin is produced from an inactive precursor, prorenin, through proteolytic cleavage at paired basic amino acid residues. In this study, an enzyme which specifically cleaves mouse Ren 2 prorenin at the paired basic residues has been purified from mouse submandibular gland by CM-Toyopearl chromatography, antipain-Sepharose chromatography, and isoelectric focusing. This enzyme, named prorenin converting enzyme, consists of two polypeptide chains of 17 and 10 kDa. The enzyme has an isoelectric point of 9.5-9.8, and its pH optimum is between 7.5 and 8.5. It specifically cleaves the peptide bond on the carboxyl side of the Arg at the Lys-Arg pair of mouse Ren 2 prorenin to yield mature renin but does not cleave mouse Ren 1 and human prorenins. Studies on the effects of inhibitors indicate that this enzyme is a serine protease that differs from the enzymes processing other prohormones at paired basic amino acid residues.