CHARACTERIZATION OF RECOMBINANT AND BRAIN NEUROPSIN, A PLASTICITY-RELATED SERINE-PROTEASE

Activity-dependent changes in neuropsin gene expression in the hippoca mpus implies an involvement of neuropsin in neural plasticity. Since t he deduced amino acid sequence of the gene contained the complete trip let (His-Asp-Ser) of the serine protease domain, the protein was postu lated to have proteolytic activity. Recombinant full-length neuropsin produced in the baculovirus/insect cell system was enzymatically inact ive but was readily converted to active enzyme by endoprotease process ing. The activational processing of prototype neuropsin involved the s pecific cleavage of the Lys(32)-Ile(33) bond near its N terminus. Nati ve neuropsin that was purified with a purity of 1,100-fold from mouse brain had enzymatic characteristics identical to those of active-type recombinant neuropsin. Both brain and recombinant neuropsin had amidol ytic activities cleaving Arg-X and Lys-X bonds in the synthetic chromo genic substrates, and the highest specific activity was found against Boc-Val-Pro-Arg-4-methylcoumaryl-7-amide. The active-type recombinant neuropsin effectively cleaved fibronectin, an extracellular matrix pro tein. Taken together, these results indicate that this protease, which is enzymatically novel, has significant limbic effects by changing th e extracellular matrix environment.