Formation in vitro of ascorbic acid 2-sulfate.

Abstract

The sulfation of ascorbic acid by an ascorbic acid sulphotransferase was investigated using rat liver and colon homogenates. When Na2 35 SO4 or 3'-phosphoadenylyl [35S]sulfate (P-Ado-P-35S) and ascorbic acid were used as substrates, chromatographic behavior of the reaction products on thin-layer cellulose suggested that ascorbic acid 2-[35S]sulfate was formed. With Na2 35SO4 as the source of radioactive sulfate in the assay system, ATP was found to be an obligatory cofactor. Incorporation of [35S]sulfate frofrom Na2 35SO4 into ascorbic acid 2-[35S]sulfate was also decreased when ATP sulfurylase inhibitors were added to the system. P-Ado-O35S alone in the assay without ATP was an extemely effective sulfating agent. In addition, liver and colon homogenates from vitamin A deficient and sufficient rats were used in one of the studies. Vitamin A deficiency appeared to have little effect on ascorbic acid 2-sulfate formation.