Leishmania mexicana mexicana gp63 is a site-specific neutral endopeptidase

Leishmania mexicana, like other species of the genus, has a major 63-kDa surface glycoprotein (gp63) that is an active protease. Reports differ as to whether gp63 is a neutral or an acidic protease. Using three radiolabeled synthetic peptide substrates, gp63 purified from L. m. mexicana is most active at pH 6.5-7.5, in three different buffer systems, and appears to be a sequence-specific endopeptidase. The full extent of sequence specificity is undetermined, but these experiments suggest a strong preference for cleavage at serine or threonine residues. In common with other metalloproteases, the cleavage is on the amino side of the recognition residue.