Degradation of human pancreastatin-52 by human kidney extract

We examined the in vitro degradation of human pancreastatin-52 (hPST-52) and a larger molecular form (approximate 15 kDa) of human PST by an enzyme extract from human kidney. The PST-degrading activity was determined from the amount of immunoreactive PST remaining after incubation of hPST-52 or the larger molecular form with the enzyme extract. Human PST-52 was degraded to smaller molecular forms within 30 min, but the larger molecule was not degraded within 90 min. Phosphoramidon, an inhibitor of endopeptidase, metal ion chelators (EDTA and 1, 10-phenanthroline) and Cu2+ prevented the degradation of hPST-52. These results indicated that the enzyme in the kidney extract degraded hPST-52 and smaller forms of the peptide, but had no effect on the 15 kDa form.