Interaction of ox heart mitochondrial F1-ATPase with immobilized ADP and ATP.
The reaction of mitochondrial F1-ATPase with immobilized substrate was studied by using columns of agarose-hexane-ATP. Mg2+ was required for binding of the enzyme to the column matrix. The column-bound enzyme could be eluted fully by ATP and other nucleoside triphosphates. Nucleoside di- and mono-phosphates were less effective. At a fixed concentration of nucleotide the effectiveness of elution was proportional to the charge on the eluting molecule. The ATP of the column matrix was hydrolysed by the bound F1-ATPase to release phosphate, probably by a uni-site reaction mechanism. Thus the F1-ATPase was bound to the immobilized ATP by a catalytic site. Treatment of the bound F1-ATPase with 4-chloro-7-nitrobenzofurazan prevented complete release of the enzyme by ATP. Only one-third of the bound enzyme was now eluted by the nucleotide. The inhibition of release could be due either to the inhibitor blocking co-operative interactions between sites or to its increasing the tightness of binding of immobilized ADP at the catalytic site.
Beharry
S
S
Department of Biochemistry, University of British Columbia, Vancouver, Canada.
Gresser
M J
MJ
Bragg
P D
PD
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000818:Animals; D001572:Benzofurans; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D002846:Chromatography, Affinity; D006586:Hexanes; D006868:Hydrolysis; D008929:Mitochondria, Heart / Q000201:enzymology*; D006180:Proton-Translocating ATPases; D012685:Sepharose; D013379:Substrate Specificity
D001572:Benzofurans; D006586:Hexanes; D000244:Adenosine Diphosphate; C059027:4-chloro-7-nitrobenzofuran; D000255:Adenosine Triphosphate; D012685:Sepharose; D006180:Proton-Translocating ATPases