The Non‐catalytic Nucleotide‐Binding Site of Mitochondrial ATPase Is Localised on the α‐Subunit(s)of Factor F1

Publisher Website
Google Scholar
Abstract
The incubation of isolated factor F1 with the di-aldehyde derivative of ADP (oxADP), which is formed as a result of ADP treatment by periodate, causes the covalent binding of 0.9-1 molecules of the oxADP with a molecule of the enzyme. This modification of factor F1 is not accompanied by changes in the ATPase activity of the enzyme. The modification of factor F1 is preceded by the reversible binding of oxADP with the enzyme with a Kd of 80 .mu.M. ADP partly prevents factor F1 from modification by oxADP. The electrophoresis of modified factor F1 in polyacrylamide gel in the presence of sodium dodecyl sulfate showed that oxADP binds with the .alpha.-subunit(s) of factor F1. When submitochondrial particles are incubated with [3H]oxADP, the main part of the radioactive label may be discovered in the polypeptide with a MW of some 30,000 which is probably the adenine nucleotides'' translocase. The isolation of factor F1 from particles preincubated with [3H]oxADP showed that the membrane-bound factor F1 covalently binds 0.2-0.3 mol of oxADP/mol of enzyme. All the oxADP is bound with the .alpha.-subunit(s) of factor F1. The modification of membrane-bound factor F1 by oxADP is accompanied by the partial inhibition of the particles'' ATPase activity. The results obtained testify to the fact that the non-catalytic site of mitochondrial ATPase located on the .alpha.-subunit(s) of factor F1 may participate in the mechanism of ATP hydrolysis by membrane-bound ATPase.

This publication has 21 references indexed in Scilit: