title: Investigation of the preferred Mg(II)-adenine-nucleotide complex at the active site of ectonucleotidases in intact vascular cells using phosphorothioate analogues of ADP and ATP.
abstract: In the presence of Mg2+ the ecto-(nucleoside diphosphatase) on intact vascular endothelial or smooth muscle cells in culture selectively catabolizes the PS diastereoisomer of adenosine 5'-[alpha-thio]diphosphate, (PS)-ADP [alpha S], and the ecto-(nucleoside triphosphatase) selectively catabolizes the PS isomer of adenosine 5'-[beta-thio]triphosphate, (PR)-ATP[beta S], but exhibits no selectivity towards ATP[alpha S] isomers. In the presence of Cd2+ selectivity to ADP[alpha S] and to ATP[beta S] isomers is reversed; in the presence of Co2+, selectivity is lost. We conclude that each enzyme preferentially recognises the lambda (screw-sense) bidentate Mg(II)-nucleotide complex at its active site.
authors.forename: J D
authors.initials: JD
authors.lastname: Pearson
authors.forename: N J
authors.initials: NJ
authors.lastname: Cusack
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000201:enzymology; D001665:Binding Sites; D001808:Blood Vessels / Q000201:enzymology*; D002478:Cells, Cultured; D008274:Magnesium / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D009708:Nucleotidases / Q000378:metabolism*; D013237:Stereoisomerism; D013552:Swine; D013873:Thionucleotides / Q000378:metabolism*
chemical_list: D000227:Adenine Nucleotides; D013873:Thionucleotides; C017817:adenosine 5'-(1-thio)triphosphate; C018444:adenosine 5'-O-(1-thiodiphosphate); C022570:adenosine 5'-O-(2-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009708:Nucleotidases; D008274:Magnesium