Species-specific charge forms of phenylethanolamine N-methyltransferase

Isoelectric points (pI) of phenylethanolamine N-methyltransferase (PNMT) from two species, cow and rat, were determined by chromatofocusing. Bovine PNMT has 5 different charge isozymes ranging from 5.4 to 6.2. In contrast, rat PNMT has only a single charge form of pI 4.8. There is no common isoelectric point of PNMT from both species and there is no tissue variation in the isoelectric point.