Cerebroside sulfotransferase in rat gastric mucosa

Abstract

1. 1. Cerebroside sulfotransferase activity was demonstrated in rat gastric mucosa. This enzyme preparation catalyzes the transfer of sulfate group from 3′-phosphoadenosine-5′-phosphosulfate to added cerebroside and lactosylceramide. 2. 2. Psychosine also serves as an acceptor for sulfate group. 3. 3. Both hydroxy-fatty acid and non-hydroxy-fatty acid containing cerebrosides are equally sulfated. However, this enzyme is inactive toward glucosylceramide. 4. 4. The optimum pH is around 6.0. The reaction is stimulated by the addition of 0.4–0.9% of Triton X-100. 5. 5. The presence of 2–4 mM ATP moderately stimulates the reaction, but is inhibitory when the concentration exceeds 6 mM. 6. 6. EDTA has no effect. 7. 7. Both Mg 2+ and Ca 2+ stimulate at lower concentrations (<16mM), but inhibit at higher concentrations (>20mM). Mn 2+, however, is a strong inhibitor even at 8mM concentration. 8. 8. The apparent K m for cerebroside is 0.04 mM, while that for 3′-phosphoadenosine-5′-phosphosulfate is 0.45 μM.