The alpha 3 beta 3 complex, the catalytic core of F1-ATPase.
- 1 September 1989
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 86 (17) , 6484-6487
- https://doi.org/10.1073/pnas.86.17.6484
Abstract
The .alpha.3.beta.3 complex was reconstituted from .alpha. and .beta. subunits of the thermophilic bacterium PS3 F1-ATPase (TF1) and then isolated. It is less stable at high and low temperatures than TF1, and the complex dissociates into subunits during native polyacrylamide gel electrophoresis. The .alpha.3.beta.3 comples has about 20% of the ATPase activity of TF1. Its enzymic properties are similar to those of the native TF1, exhibiting similar cooperative kinetics as a fundtion of ATP concentration, similar substrate specificity for nucleotide triphosphates, and thepresence of two peaks in its temperatures-activity profile. Differing from TF1, the ATPase activity of the .alpha.3.beta.3 comples is insensitive to N3- inhibition, its divalent cation specificity is less stringent, and its optimum pH shifts to the alkaline side. The addition of the .gamma. subunit of the .alpha.3.beta.3 complex leads to the formation of the .alpha.3.beta.3.gamma. complex, indicating that the .alpha.3.beta.3 complex is an intermediate in the process of assembly of the holoenzyme from each subunit. These results definitely show that the essential structure for eliciting the ATPase activityof F1-ATPase is trimeric .alpha..beta. pairs and that the kinetic cooperativity of the F1-ATPase is an inherent property of this trimeric structure but is not due to the presence of single-copy subunits. in this sense, the .alpha.3.beta.3 complex is the catalytic core of F1-ATPase.This publication has 22 references indexed in Scilit:
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