title: Beta-selenaproline as competitive inhibitor of proline activation.
abstract: Beta-Selenaproline, a proline analog having the beta-methylene group substituted by a selenium atom, has been tested in ATP-PPi exchange reaction catalyzed by either Escherichia coli or rat liver aminoacyl-tRNA synthetases. It has been shown that with both enzymatic systems beta-selenaproline does not give rise to ATP-PPi exchange, but specifically inhibits proline activation. The inhibition is of fully competitive type and the Ki values, lower than the Km values for proline, show that beta-selenaproline binds to the synthetases with high affinity. The inability to form the complex with AMP, taking into account also the behavior of gamma-selenaproline and other proline analogs, has been ascribed to the presence of the selenium atom in the beta-position.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D000818:Animals; D011756:Diphosphates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D016566:Organoselenium Compounds; D011392:Proline / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D012643:Selenium / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011756:Diphosphates; D016566:Organoselenium Compounds; C014811:selenaproline; D000255:Adenosine Triphosphate; D011392:Proline; D000604:Amino Acyl-tRNA Synthetases; D012643:Selenium