EXPRESSION OF RECOMBINANT PRO-NEUROPEPTIDE-Y, PROOPIOMELANOCORTIN, AND PROENKEPHALIN - RELATIVE PROCESSING BY PROHORMONE THIOL PROTEASE (PTP)

The preference of the 'prohormone thiol protease' (PTP), a candidate p rohormone processing enzyme, for different peptide precursors was asse ssed in vitro with recombinant prohormones near estimated in vivo leve ls. Pro-neuropeptide Y (pro-NPY), proopiomelanocortin (POMC), and proe nkephalin (PE) were expressed at high levels in E. coli. Purification of prohormones utilized a combination of DEAE-Sepharose, Mono Q, and p reparative electrophoresis. PTP cleaved PE most readily, and also clea ved pro-NPY, The processing of POMC by PTP was minimal, These results demonstrate PTP's preference for certain prohormone substrates.