Beharry S, Bragg P D
Department of Biochemistry, University of British Columbia, Vancouver, Canada.
Biochem J. 1992 Sep 1;286 ( Pt 2)(Pt 2):603-6. doi: 10.1042/bj2860603.
Escherichia coli F1-ATPase contained 2.9 +/- 0.1 mol of adenine nucleotide and 3.1 +/- 0.3 mol of Pi/mol of enzyme. After preincubation with ATP, the nucleotide and phosphate contents were 5.6 and 6.0 +/- 0.5 mol/mol of enzyme respectively. The F1-ATPase was induced to synthesize ATP in the presence of 30% (v/v) dimethyl sulphoxide (Me2SO). The ATP originated from endogenous bound ADP. The bound adenine nucleotide and Pi contents of the enzyme during the time course of ATP synthesis were investigated by using F1-ATPase which had been preincubated with ATP. We show that the process of ATP synthesis in Me2SO involves (i) an initial rapid loss of nucleotide from the enzyme, the process being facilitated by exogenous Pi, (ii) a rapid loss of Pi from the enzyme, at least in the absence of exogenous Pi, (iii) re-binding of a portion of the lost nucleotide, and (iv) synthesis of ATP from bound ADP and exogenous Pi. It is proposed that transfer of the F1-ATPase to the Me2SO medium induces a change in the conformation of the enzyme to a form favouring ATP synthesis.
大肠杆菌F1 - ATP酶每摩尔酶含有2.9±0.1摩尔腺嘌呤核苷酸和3.1±0.3摩尔磷酸根离子。用ATP预孵育后，核苷酸和磷酸根含量分别为每摩尔酶5.6摩尔和6.0±0.5摩尔。在30%（v/v）二甲基亚砜（Me2SO）存在下，F1 - ATP酶被诱导合成ATP。ATP来源于内源性结合的ADP。通过使用已用ATP预孵育的F1 - ATP酶，研究了ATP合成过程中酶结合的腺嘌呤核苷酸和磷酸根离子含量。我们发现，在Me2SO中ATP合成过程包括：（i）酶最初快速失去核苷酸，该过程由外源磷酸根离子促进；（ii）酶快速失去磷酸根离子，至少在没有外源磷酸根离子的情况下如此；（iii）一部分丢失的核苷酸重新结合；（iv）由结合的ADP和外源磷酸根离子合成ATP。有人提出，将F1 - ATP酶转移到Me2SO培养基中会诱导酶的构象发生变化，转变为有利于ATP合成的形式。
