Neurolysin activities

The enzyme in cell extracts that is able to cleave most antigenic peptides is the thimet endooligopeptidase [EC 3.4.24.15 or TOP] [361]. Primarily cytosolic, this enzyme may also be expressed as a membrane-associated form [362]. TOP and neurolysin activities in melanoma cells were found in the culture medium and tumor cell membrane in addition to their cytosolic expression (Paschoalin, T. and Travassos, L.R., unpublished results). Different roles have been attributed to TOP particularly in the neuropeptide metabolism [363,364]. 

Recombinant TOP and neurolysin activities were compared using seven series of peptides based on Abz-GFSPFRQ-EDDnp, an internally quenched fluorogenic substrate [377]. Most of the peptides were hydrolyzed at the bond corresponding to P(4)-F(5) in the reference substrate. Others were cleaved at this bond or at F(2)-S(3). The best substrates for TOP had at P(l), Phe, Ala or Arg and for neurolysin, Asn or Arg. 

---