Alterations of glycosidases in human colonic adenocarcinoma.
OBJECTIVE
We have carried out a detailed study of some glycosidases in an attempt to explain the differential profile of enzyme activity between human colonic adenocarcinoma and normal mucosa.


METHODS
Several glycosidase activities associated with human colonic adenocarcinoma 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-galactosaminidase activities. Tumoral tissue showed higher beta-D-galactosidase, beta-NAc-D-glucosaminidase, and beta-NAc-D-galactosaminidase activities than control tissue. Glycosidases from tumoral and control tissues demonstrated no differences in optimum pH, subcellular distribution, pH and thermal stability. However, the kinetic analysis showed a statistically significant increased Vmax in tumoral colon with respect to the control for beta-D-galactosidase, beta-NAc-D-glucosaminidase, and beta-NAc-D-galactosaminidase activities. The Km remained unaltered.


CONCLUSIONS
The increased Vmax 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.
Gil-Martín
E
E
Department of Fundamental Biology, Faculty of Sciences, University of Vigo, Spain.
Rodríguez-Berrocal
J
J
Páez de la Cadena
M
M
Fernández-Briera
A
A
D000118:Acetylglucosaminidase / Q000378:metabolism; D000230:Adenocarcinoma / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D003110:Colonic Neoplasms / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008361:Mannosidases / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D043323:alpha-Mannosidase; D001616:beta-Galactosidase / Q000378:metabolism
D006026:Glycoside Hydrolases; D008361:Mannosidases; D001616:beta-Galactosidase; D043323:alpha-Mannosidase; D000118:Acetylglucosaminidase