Functional molecular masses of vacuolar membrane H+‐ATPase from Saccharomyces cerevisiae as studied by radiation inactivation analysis

FEBS Letters

Hirata, Ryogo¹  Ohsumi, Yoshinori¹  Anraku, Yasuhiro¹ 

[1]Department of Biology, Faculty of Science, University of Tokyo, Hongo, Tokyo 113, Japan

关键词: Vacuolar membrane;    ATPase;    H+-;    Molecular mass;    functional;    Radiation inactivation analysis;   

DOI  :  10.1016/0014-5793(89)80571-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The functional molecular masses of the vacuolar membrane H⁺-ATPase in Saccharomyces cerevisiae under two kinetic conditions for ATP hydrolysis were measured by radiation inactivation. When vacuolar membrane vesicles were exposed to γ-rays from ⁶⁰Co, the activities catalyzing a single-cycle and multi-cycles of ATP hydrolysis both decreased as single-exponential functions of the radiation dosage. By applying the target theory, the functional molecular masses for single-and multi-cycle hydrolyses of ATP were determined to be approx. 0.9–1.1 × 10⁵ and 4.1–5.3 × 10⁵ Da, respectively. N,N′-Dicyclohexylcarbodiimide (DCCD) did not inhibit the former reaction but strongly inhibited the latter. It is suggested that the ATPase with a minimal composite of subunits a and b, in which subunit c is not necessarily involved operationally, can catalyze single-cycle hydrolysis of ATP, whereas for multi-cycle hydrolysis of ATP, the ATPase requires a properly organized oligomeric structure with subunits a–c, which may direct a positive cooperative mechanism of ATP hydrolysis and coupled H⁺ translocation in a DCCD-sensitive manner.

【 授权许可】

Unknown