Inhibitory effect of NaN3 on the F0F1 ATPase of submitochondrial particles as related to nucleotide binding.
The inhibitory effects of NaN3 on the F0F1 ATPase of beef heart submitochondrial particles were investigated. It was shown that NaN3 inhibited the ATPase activity only in the presence of ATP or ADP and the inhibition proceeded slowly. Analysis of the time-course of the inhibition process lead to a conclusion that an ATP binding site which has an apparent Kd of 14.0 +/- 8.7 microM is responsible for the increase of NaN3 sensitivity. This value agreed well with the low Km of ATP hydrolysis characterized before (Muneyuki, E., and Hirata, H. (1988) FEBS Lett. 234, 455-458) and in the range of so-called bi-site catalysis. The same conclusion was derived as for isolated F1 ATPase. From similar analysis, the Kd of this site for ADP was deduced to be 1.34 +/- 0.45 microM, which also agreed with that reported by Pedersen (Pedersen, P.L. (1975) Biochem. Biophys. Res. Commun. 64, 610-616) and also in the same range as reported for the low Km of ATP synthesis by activated submitochondrial particles. These results suggest that hydrolysis through the low Km mode of ATPase reaction leads the enzyme NaN3 sensitive form and this reaction cycle corresponds to the low Km mode of ATP synthesis.
Muneyuki
E
E
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Japan.
Makino
M
M
Kamata
H
H
Kagawa
Y
Y
Yoshida
M
M
Hirata
H
H
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000495:Allosteric Site; D000818:Animals; D001386:Azides / Q000494:pharmacology*; D002417:Cattle; D066298:In Vitro Techniques; D008956:Models, Chemical; D010710:Phosphates / Q000494:pharmacology; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019810:Sodium Azide; D013367:Submitochondrial Particles / Q000201:enzymology*
D001386:Azides; D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D019810:Sodium Azide; D006180:Proton-Translocating ATPases