Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.109 (AST)
 6,066 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytosolic sulfotransferases, which consist of at least three gene families, play a major role in activation and detoxification of both endogenous and exogenous chemicals. We recently purified a rabbit sulfotransferase, AST-RB2, showing high activities to both hydroxysteroids and amines. To characterize this enzyme, a rabbit cDNA library was screened using anti-AST-RB2 antibodies. The isolated cDNA was judged to encode AST-RB2 (ST2A8) based on the amino acid sequences of peptide fragments obtained from purified AST-RB2. The cDNA showed high similarity to other mammalian hydroxysteroid sulfotransferases (ST2) at the amino acid level (58-68%), but low similarity to aryl sulfotransferases (ST1) (less than 37%). The protein expressed in Escherichia coli catalyzed sulfation of typical ST2 substrates. Therefore, ST2A8 was judged to belong to the ST2 family from both its primary structure and substrate specificity. The ST2A8 protein expressed in E. coli clearly differed from rat ST2A1 and ST2A2 on its localization (cytosol/insoluble fraction ratio). ST2A8 had no activity to lithocholate, but showed the highest catalysis on dehydroepiandrosterone and testosterone among the four forms (ST2A1, ST2A2, ST2A3, and ST2A8), indicating a clear difference between ST2A forms in substrate specificity to endogenous chemicals.
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PMID:Molecular cloning, expression, and enzymatic characterization of rabbit hydroxysteroid sulfotransferase AST-RB2. 953 69

Two sulfotransferases (STs), designated as AST-RB1 (ST3A1) and AST-RB2 (ST2A8), with high a amine N-sulfonating activity, were purified from male rabbit liver cytosols. AST-RB1 and AST-RB2 were purified to homogeneity by the anion-exchange, affinity, and hydroxyapatite chromatography. The N-terminus of both enzymes were blocked. The subunit molecular mass of both enzymes was estimated to be 34 kDa on SDS-PAGE. AST-RB1 efficiently catalyzed N-sulfonation of alicyclic, alkyl, and arylamines such as 4-phenyl-1,2,3, 6-tetrahydropyridine, 1-[(5-chloro-2-oxo-3(2H)-benzothiazolyl)acetyl]-piperazine, desipramine, and aniline, whereas its catalytic activities toward 2-naphthol and dehydroepiandrosterone (DHEA) were very low. On the other hand, AST-RB2 efficiently catalyzed sulfonation of desipramine and DHEA, but had no activity toward 2-naphthol. Amino acid sequences of peptide fragments derived from the purified AST-RB1 showed no significant homology with previously reported STs, but those from the purified AST-RB2 shared a high similarity with those of the ST2 family. Both enzymes were expressed specifically in the liver. The present results strongly suggest that the purified AST-RB1 is a novel enzyme in terms of structure and catalytic properties showing high selectivity for amine substrates, and AST-RB2 is a quite unique from among ST2A enzymes of other species in its substrate specificity.
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PMID:Purification and characterization of two amine N-sulfotransferases, AST-RB1 (ST3A1) and AST-RB2 (ST2A8), from liver cytosols of male rabbits. 998 35