ascorbic-acid-2-sulfate and 4-methylumbelliferyl-sulfate

Ascorbic acid-2-sulfatase was isolated from rat liver by a multistep procedure. DEAE Sephacel ion-exchange chromatography resolved crude ascorbic acid-2-sulfatase into cationic and anionic fractions. These fractions were purified 75- and 230-fold, respectively. The comparative biochemical properties suggest that arylsulfatase B is responsible for the cationic ascorbic acid-2-sulfatase activity, while arylsulfatase A appears to be responsible for the anionic ascorbic acid-2-sulfatase activity. Partially purified arylsulfatase A hydrolyzed ascorbic acid-2-sulfate at 4% the rate of p-nitrocatechol sulfate hydrolysis, while arylsulfatase B hydrolyzed ascorbic acid-2-sulfate at 0.6% the p-nitrocatechol sulfate rate.

Topics: Animals; Arylsulfatases; Ascorbic Acid; Catechols; Cerebroside-Sulfatase; Chondro-4-Sulfatase; Chromatography, Ion Exchange; Hymecromone; Liver; Rats; Rats, Inbred Strains; Substrate Specificity; Sulfatases

Rabbit liver aryl sulfatase A (aryl-sulfate sulfohydrolase, EC 3.1.6.1) is a glycoprotein containing 4.6% carbohydrate in the form of 25 residues of mannose, seven residues of N-acetylglucosamine, and three residues of sialic acid per enzyme monomer of molecular weight 140 000. Each monomer consists of two equivalent polypeptide chains. The protein has a relatively high content of proline, glycine and leucine, and the amino acid composition of rabbit liver aryl sulfatase A is similar to that of other known liver sulfatases. Rabbit liver aryl sulfatase A catalyzes the hydrolysis of a wide variety of sulfate esters, although it appears possible that cerebroside sulfate is a physiological substrate for the enzyme because the Km is very low (0.06 mM). The turnover rate for hydrolysis of nitrocatechol sulfate or related synthetic substrates is much higher than the rate with most naturally occurring sulfate esters such as cereroside sulfate, steroid sulfates, L-tyrosine sulfate or glucose 6-sulfate. However, the turnover rate with ascorbate 2-sulfate is comparable to the rates measured using most synthetic substrates. These results are discussed in relationship to several previously described sulfatase enzymes which were claimed to have unique specificities.

Topics: Amino Acids; Animals; Ascorbic Acid; Carbohydrates; Catalysis; Catechols; Cerebroside-Sulfatase; Cerebrosides; Hydrolysis; Hymecromone; Kinetics; Liver; Nitrobenzenes; Rabbits; Substrate Specificity; Sulfatases; Sulfuric Acids; Tyrosine