Effect of ethanol on the enzymatic sulfation of glycosphingolipids in gastric mucosa.
The enzyme activity which catalyzes the transfer of sulfate group from 3'-phosphoadenosine 5'-phosphosulfate to C-3 of the galactose residue of galactosylceramide and lactosylceramide has been demonstrated in the Triton X-100 extracts of the microsomal fraction of rat gastric mucosa. The sulfotransferase activity of this fraction in antral mucosa was 1.2-1.3 times greater than that of the body and 19-22 times greater than that of the forestomach. The enzyme did not catalyze the transfer of sulfate to glucosylceramide, trihexosylceramide, and triglucosyl monoalkylmonoacylglycerol. Optimum enzymatic activity was obtained using 0.4% Triton X-100, 33 mM NaF, and 15 mM MgCl2 at a pH of 6.8. The sulfotransferase activity was inhibited by ethanol. With both glycolipid substrates, little inhibition of enzyme activity was obtained up to 0.5 M ethanol. However, higher concentrations of ethanol produced severe inhibitory effect. This inhibition of sulfation of galactosylceramide and lactosylceramide by ethanol was of the competitive type. The apparent KI values were 8.3 X 10(-5) for galactosylceramide and 5.6 X 10(-5) for lactosylceramide.
D000818:Animals; D000431:Ethanol / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects / Q000201:enzymology*; D006028:Glycosphingolipids / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity; D015238:Sulfotransferases; D013466:Sulfurtransferases / Q000378:metabolism*
D006028:Glycosphingolipids; D000431:Ethanol; D013466:Sulfurtransferases; D015238:Sulfotransferases; C020556:galactosylceramide sulfotransferase