ALTERATIONS OF GLYCOSIDASES IN HUMAN COLONIC ADENOCARCINOMA

Objectives: We have carried out a detailed study of some glycosidases in an attempt to explain the differential profile of enzyme activity b etween human colonic adenocarcinoma and normal mucosa. Design and Meth ods: Several glycosidase activities associated with human colonic aden ocarcinoma and control tissues were submitted to a detailed structural and functional characterization. Results: Tumoral and control samples were assayed for beta-D-galactosidase, beta-D-glucuronidase, alpha-D- mannosidase, beta-NAc-D-glucosaminidase and beta-NAc-D-galactosaminida se activities. Tumoral tissue showed higher beta-D-galactosidase, beta -NAc-D-glucosaminidase, and beta-NAc-D-galactosaminidase activities th an control tissue. Glycosidases from tumoral and control tissues demon strated no differences in optimum pH, subcellular distribution, pH and thermal stability. However, the kinetic analysis showed a statistical ly significant increased V-max in tumoral colon with respect to the co ntrol for beta-D-galactosidase, beta-NAc-D-glucosaminidase, and beta-N Ac-D-galactosaminidase activities. The K-m remained unaltered. Conclus ions: The increased V-max detected for some glycosidase activities in human colonic adenocarcinoma could correspond with a greater presence of enzyme proteins in the tumoral cells, and not to changes in protein and/or active site structure.