Highly sensitive assay for PZ-peptidase activity by high-performance liquid chromatography.

A rapid and highly sensitive assay method for measuring PZ-peptidase activity in newborn rat brain is described. The method is based on monitoring the absorption at 320 nm of PZ-Pro-Leu enzymatically formed from the substrate, PZ-L-Pro-L-Leu-Gly-L-Pro-D-Arg, after separation by high-performance liquid chromatography using a reversed-phase column. This method is sensitive enough to measure PZ-Pro-Leu at concentrations as low as 5 pmol, and is able to make the column ready for the next injection within 10 min after the preceding injection. By using this method, PZ-peptidase activity was discovered in clonal osteoblastic cells derived from newborn mouse calvaria.