Guanidinobenzoatases are cell surface-associated
proteinases supposed to be involved in
cancer metastasis, cell migration, and tissue remodeling. The main features of the
guanidinobenzoatase associated with human
renal carcinoma plasma membrane are weak membrane association, continuous cleavage of
p-nitrophenyl-p'-guanidinobenzoate conversely to the site titration effect of this compound when used with
trypsin, and a peculiar sensitivity to
serine protease inhibitors, compatible with a poorly active form. Plasma membrane preparation followed by
agmatine-trisacryl affinity chromatography allows the purification of
guanidinobenzoatase to homogeneity with an apparent enrichment factor of 450. Purified
guanidinobenzoatase appears as a single
polypeptide chain of M(r) 80,000, likely stabilized by intrachain
disulfides bonds. The properties of purified
guanidinobenzoatase indicate that it is an original
enzyme in spite of some similarities with
plasminogen activators. Indeed, in addition to differences in substrate and inhibitor specificity,
guanidinobenzoatase is not recognized by specific
monoclonal antibodies directed against
plasminogen activators or their single-chain precursors. Thus, human
renal carcinoma guanidinobenzoatase appears to be an original
enzyme whose activity is undetectable in the nontumoral tissue of origin. In this respect, use of purified
guanidinobenzoatase would allow us to obtain specific tools to give new insights in
cancer cell
metastasis.