Premium
The sulphydryl content of yeast mitochondrial F 1 ‐ATPase and the stoichiometry of subunits
Author(s) -
Gregory Roland,
Hess Benno
Publication year - 1981
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(81)80167-6
Subject(s) - citation , combinatorics , physics , philosophy , mathematics , library science , computer science
Mitochondrial coupling factor F1-ATPase catalyzes the hydrolysis of ATP. The structure of this multisubunit enzyme is complex [ 1,2] and the exact stoichiometry of the 5 subunits is still not clear, the choice lying between (Y&$E and az&~&ez (or similar) [2,3]. A stoichiometry of 3:3:1:1:1 for CX$:T:~ :E, respectively, is likely in the case of yeast F1-ATPase [4-61, F1-ATPase of thermophilic bacterium [7] and Escherkhia coli [8], and this stoichiometry may be universal for F1-ATPase [9]. Because the sulphydryl content of a protein is usually very low, titration or specific labelling of sulphydryl side-chain groups offers a means of determining their number and distribution, and hence obtaining chemically the subunit stoichiometry, in the case of a multi-subunit enzyme. Using this approach with the yeast F1-AT’Pase we show that: (1) The F1-ATPase contains no disulphide linkages; (2) Only the (Y-, yand &subunits contain sulphydryl groups; (3) The stoichiometry of a:y:6 is 3: 1: 1. From this distribution and from the yeast mitochondrial F,-ATPase MI of 390 000 [IO], a stoichiometry of a&-y& is obtained.