[Characteristics of cysteine peptidohydrolases from the human kidney cortex]

Spectrum of cysteine peptide hydrolases was studied in human kidney cortex using a variety of protein and synthetic substrates after the preparation was fractionated on Sephadex G-100 following the precipitation with ammonium sulfate 40-70%. Activities of dipeptidyl aminopeptidase I, lysosomal carboxypeptidases A and B, cathepsins B and H, as well as the activity of Ca+2-dependent neutral proteinase were detected. A thiol-dependent proteolytic activity, which was apparently stimulated by cathepsin T- and -M like enzymes, was also observed. Besides, the proteinase with molecular mass of 50-60 KDa and high hemoglobin and casein splitting activity was found. This activity cannot be attributed to any of the proteinases so far known. Isoelectrofocusing technique showed that two forms of cathepsin B occurred in human kidney with isoelectric points at pH 5.32 and pH 5.65; two forms of cathepsin H were also detected exhibiting isoelectric points at pH 6.03 and pH 6.7.