Steady-state kinetic study on the inhibition of the adenosinetriphosphatase activity of dynein from Tetrahymena cilia by glycerol.
The characteristics of glycerol-induced inhibition of the dynein ATPase extracted from Tetrahymena cilia were investigated. Fifty percent inhibition was observed at about 15% (v/v) glycerol with the 22S dynein Mg-ATPase. Ethylene glycol was equally inhibitory, while sucrose, a kind of polyol, was less effective. The glycerol-induced inhibition of the 22S dynein Mg-ATPase was not influenced by pH or by raising the ionic strength of the assay solution. An aqueous glycerol solution treated with anion or cation exchanger or charcoal was equally inhibitory to a non-treated solution. The inhibition was most likely to be due to glycerol or ethylene glycol itself, not to a contaminant. The inhibition of the 22S dynein Mg-ATPase was apparently noncompetitive: only the Vmax was reduced without a significant change in the apparent Km. The dynein ATPase is known to be inhibited potently by vanadate. Glycerol reduced the sensitivity of the dynein ATPase to the vanadate-induced inhibition. Glycerol exhibited a decelerating effect on the rate of the oxygen exchange between phosphate and water catalyzed by 22S dynein in the presence of ADP and Mg2+. If it is assumed that the rate constants of the ATP hydrolysis step are not affected by glycerol, it may be implied that the phosphate release from the E.ADP.P1 intermediate was decelerated by glycerol and that the deceleration of the phosphate release paralleled the reduction of the overall ATPase activity over a wide range of glycerol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
Shimizu
T
T
Research Institute for Polymers and Textiles, Ibaraki.
Katsura
T
T
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors*; D002923:Cilia / Q000201:enzymology; D004398:Dyneins / Q000037:antagonists & inhibitors*; D019855:Ethylene Glycol; D005026:Ethylene Glycols / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013395:Sucrose / Q000494:pharmacology; D013769:Tetrahymena pyriformis / Q000201:enzymology*
D005026:Ethylene Glycols; D013395:Sucrose; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D004398:Dyneins; D019855:Ethylene Glycol; D005990:Glycerol