AJP - Gastrointestinal and Liver Physiology, Vol 242, Issue 5 442-G447, Copyright © 1982 by American Physiological Society
Effect of ethanol on peptidases of hamster jejunal brush-border membrane
P. K. Dinda and I. T. Beck
This study was undertaken to investigate the effect of ethanol on the
brush-border activity of the small intestine. Brush-border membrane
isolated from hamster jejunum was incubated with L-phenylalanylglycine
(Phe-Gly), L-leucylglycine (Leu-Gly), or glycyl-L-tyrosine (Gly-Tyr) in the
absence and presence of 1-5% (wt/vol) ethanol, and the L-amino acids
liberated were determined. Ethanol was found to depress the hydrolysis of
all peptides in a dose-dependent manner. The inhibitory effect of ethanol
on the peptidases does not appear to be time dependent. The ethanol-induced
inhibition of peptidase activity is completely reversible. Kinetic studies
indicate that ethanol caused a decrease in the Vmax of the enzymes
responsible for the hydrolysis of the Phe-Gly and Gly-Tyr but did not have
any effect on their Km. In the hydrolysis of Leu-Gly, two enzymes were
involved, and ethanol depressed the Vmax of both without affecting the Km
of either. These findings suggest that ethanol produces conformational
changes of the peptidases involved in the hydrolysis of these three
dipeptides.
