title: Pterin deaminase from Bacillus megaterium. Purification and properties.
abstract: A pterin deaminase catalyzing the hydrolytic deamination of various pteridines was found in the bacterium, Bacillus megaterium, and partially purified from bacterial extract. The specific activity was raised 90-fold over that of the crude extract. The pH optimum is around 7.3, and the Km value for 6-carboxypterin is 1.3 mM. The molecular weight of the enzyme was estimated by gel filtration to be about 110,000. The enzyme deaminated pterin, 6-carboxypterin, biopterin, 6-methylpterin, 7-methylpterin, xanthopterin, 6-hydroxymethylpterin, sepiapterin, isosepiapterin, folic acid, and 6,7-dimethylpterin to their corresponding lumazines, whereas guanine, 7-carboxypterin, leucopterin, isoxanthopterin, and 6-methylisoxanthopterin did not serve as substrates. The enzyme was inhibited by PCMB and 8-azaguanine.
mesh_terms: D000619:Aminohydrolases / Q000302:isolation & purification / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism; D001375:Azaguanine / Q000494:pharmacology; D001410:Bacillus megaterium / Q000201:enzymology*; D002729:Chloromercuribenzoates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D011622:Pterins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D002729:Chloromercuribenzoates; D011622:Pterins; D000641:Ammonia; D000619:Aminohydrolases; D001375:Azaguanine