The substrate specificity of dynein from Tetrahymena cilia.
The substrate specificity of the 22S dynein ATPase from Tetrahymena cilia was investigated. The 22S dynein exhibited a high specificity for ATP in terms of both apparent Km and Vmax: naturally occurring nucleoside triphosphates other than ATP were hydrolyzed slowly with an apparent Km of 0.25-1 mM, a sharp contrast to that of ATP hydrolysis (1-4 microM). Pyrophosphate was a poor inhibitor for the dynein ATPase, indicating weak affinity. Since dynein binds ATP tightly and hydrolyzes it at a high rate, a method to determine a trace amount of ATP in the presence of other nucleoside triphosphates has been developed by taking advantage of this enzymatic characteristic of dynein. The effect of P1,P5-di(adenosine-5'-)-pentaphosphate (Ap5A) on the 22S dynein ATPase was also investigated. Ap5A acted as a weak competitive inhibitor of the ciliary 22S dynein ATPase and the nonlinearity of the double-reciprocal plot of the ATPase was confirmed in the presence of Ap5A.
Shimizu
T
T
Research Institute for Polymers and Textiles, Ibaraki.
D000227:Adenine Nucleotides / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D015226:Dinucleoside Phosphates; D011756:Diphosphates / Q000494:pharmacology; D004398:Dyneins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D007293:Inosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D013379:Substrate Specificity; D013768:Tetrahymena / Q000201:enzymology*
D000227:Adenine Nucleotides; D015226:Dinucleoside Phosphates; D011756:Diphosphates; D007293:Inosine Triphosphate; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004398:Dyneins