Premium
The ‘non‐exchangeable’ nucleotides of F 1 ‐F 0 )ATP synthase
Author(s) -
Harris David A.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81295-b
Subject(s) - nucleotide , chemistry , atp synthase , stereochemistry , glycogen phosphorylase , biochemistry , carbamoyl phosphate synthetase , enzyme , phosphate , gene
The F 1 ‐F o ATP synthase bears 6 nucleotide binding sites, only 3 of which turn over during catalysis. The remaining 3 are occupied by slowly exchanging ATP in vivo, although at least 1 molecule is generally lost on isolation of the enzyme in the absence of nucleotide. It is proposed that the function of the slowly exchanging (NC) nucleotides is to participate in catalysis, the terminal phosphate of the bound ATP acting as an acid catalyst in the cleavage/synthesis of the phosphate anhydride bond in the catalytic sites. Such a role has been demonstrated for the bound pyridoxal phosphate moiety in glycogen phosphorylase. Evidence is presented that (i) the NC nucleotide spans the interface between an α subunit and its partner β, interacting near the catalytic binding site on β; (ii) the phosphate moieties of the catalyzed and NC nucleotide are close in space; and (iii) occupation of the NC nucleotide sites promotes ATP hydrolysis by F 1 or its subfragments. All of these findings are required by the proposed mechanism. Relationships between phosphorylase and F 1 structures are discussed.