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Isolation and properties of a natural inhibitor of the chloroplast adenosine triphosphatase
Author(s) -
Younis Hassan M.,
Morjaihmat A.
Publication year - 1982
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(82)80924-1
Subject(s) - isolation (microbiology) , adenosine triphosphatase , chemistry , chloroplast , natural (archaeology) , adenosine , biochemistry , biology , atpase , enzyme , microbiology and biotechnology , gene , paleontology
The membranous reversible H’-ATPase complex of mitochondria, bacteria and chloroplasts has been shown to be the functional component in generating ATP [ 11. Structural and functional properties of this ATPase from different sources were found to be similar in many respects [2,3]. The mechanism by which this proton-pumping ATPase functions is still unknown. Control of the system in mitochondria by an endogenous protein inhibitor of the ATPase was first described in [4]. This protein is an easily dissociated subunit of the ATPase complex which specifically and effectively inhibits the ATPase activity of mitochondria [5]. Further studies have underlined the regulatory function of this protein in oxidative phosphorylation as well as in the back flow of energy from ATP [5]. Here, we demonstrate that a similar chloroplast ATPase protein inhibitor could be solubilized by heat treatment of the chloroform-released 7 subunit enzyme or any of the preparations containing the 10 000 Mr subunit, CZ [6]. The properties of this inhibitor were studied. It was sensitive to trypsin. It inhibited membrane-bound chloroplast Mg*+ATPase and soluble CF 1 -ATPase. This inhibition was pH-dependent and was stimulated by Mg*+ and ATP. It did not inhibit the particulate or soluble mitochondrial ATPase activity from bovine heart or insect flight muscles.