Two distinct types of ɛ‐binding site exist in chloroplast coupling factor (CF1)

FEBS Letters

Harris, D.A.¹  Andralojc, P.J.¹ 

[1] Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, England

关键词: Chloroplast;    ATP synthase;    F1-ATPase;    ATPase inhibitor protein;    Subunit interaction;    CF1;    chloroplast coupling factor 1;    F1;    coupling factor 1;    DTT;    DL-dithiothreitol;    IBZ;    o-iodosobenzoate;    TEA;    triethanolamine;    tricine N-tris(hydroxymethyl)-methylglycine;    Tris;    tris(hydroxymethyl)aminomethane;    SDS-PAGE;    SDS-polyacrylamide gel electrophoresis;   

DOI  :  10.1016/0014-5793(88)80471-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Isolated chloroplast coupling factor (CF₁), when depleted of its ɛ-subunit, has a high ATPase activity which can be inhibited by binding ɛ to a single high-affinity (K _d = 1.4 × 10⁻¹⁰ M) site. In CF₁ reduced by dithiothreitol (DTT), however, ɛ at this binding site is no longer inhibitory. Instead, 3 equivalent, lower affinity (K _d = 6 × 10⁻⁸ M), inhibitory binding sites for ɛ are observed, whether or not the high-affinity site contains a bound ɛ-subunit. Binding of ɛ to the high-affinity site protects CF₁ against trypsin activation, while binding to the low-affinity site does not, showing that occupation of each class of site has a different effect on CF₁ structure. The effects of DTT can be interpreted in terms of a reduction in intersubunit cooperativity in CF₁.

【 授权许可】

Unknown