Functional molecular masses of vacuolar membrane H+-ATPase from Saccharomyces cerevisiae as studied by radiation inactivation analysis.
FEBS Lett
; 244(2): 397-401, 1989 Feb 27.
Article
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| MEDLINE
| ID: mdl-2522060
ABSTRACT
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 gamma-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 X 10(5) and 4.1-5.3 X 10(5) 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.
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Banco de datos:
MEDLINE
Asunto principal:
Saccharomyces cerevisiae
/
Vacuolas
/
ATPasas de Translocación de Protón
Idioma:
En
Año:
1989
Tipo del documento:
Article