Beharry S, Bragg P D
Department of Biochemistry, University of British Columbia, Vancouver, Canada.
Biochem Cell Biol. 1991 Apr;69(4):291-6. doi: 10.1139/o91-044.
Dimethylsulfoxide (Me2SO; 30%, v/v) promotes the formation of ATP from ADP and phosphate catalyzed by soluble mitochondrial F1 ATPase. The effects of this solvent on the adenine nucleotide binding properties of beef-heart mitochondrial F1 ATPase were examined. The ATP analog adenylyl-5'-imidodiphosphate bound to F1 at 1.9 and 1.0 sites in aqueous and Me2SO systems, respectively, with a KD value of 2.2 microM. Lower affinity sites were present also. Binding of ATP or adenylyl-5'-imidodiphosphate at levels near equimolar with the enzyme occurred to a greater extent in the absence of Me2SO. Addition of ATP to the nucleotide-loaded enzyme resulted in exchange of about one-half of the bound ATP. This occurred only in an entirely aqueous medium. ATP bound in Me2SO medium was not released by exogenous ATP. Comparison of the effect of different concentrations of Me2SO on ADP binding to F1 and ATP synthesis by the enzyme showed that binding of ADP was diminished by concentrations of Me2SO lower than those required to support ATP synthesis. However, one site could still be filled by ADP at concentrations of Me2SO optimal for ATP synthesis. This site is probably a noncatalytic site, since the nucleotide bound there was not converted to ATP in 30% Me2SO. The ATP synthesized by F1 in Me2SO originated from endogenous bound ADP. We conclude that 30% Me2SO affects the adenine nucleotide binding properties of the enzyme. The role of this in the promotion of the formation of ATP from ADP and phosphate is discussed.
二甲基亚砜（Me2SO；30%，v/v）可促进可溶性线粒体F1 ATP酶催化二磷酸腺苷（ADP）和磷酸盐形成三磷酸腺苷（ATP）。研究了该溶剂对牛心线粒体F1 ATP酶的腺嘌呤核苷酸结合特性的影响。在水性体系和Me2SO体系中，ATP类似物腺苷 - 5'-亚氨二磷酸分别以1.9个和1.0个位点与F1结合，解离常数（KD）值为2.2微摩尔。也存在较低亲和力的位点。在不存在Me2SO的情况下，与酶等摩尔水平的ATP或腺苷 - 5'-亚氨二磷酸的结合程度更高。向加载了核苷酸的酶中添加ATP会导致约一半结合的ATP发生交换。这仅发生在完全水性的介质中。在Me2SO介质中结合的ATP不会被外源ATP释放。比较不同浓度的Me2SO对ADP与F1结合以及该酶合成ATP的影响表明，低于支持ATP合成所需浓度的Me2SO会减少ADP的结合。然而，在对ATP合成最适宜的Me2SO浓度下，一个位点仍可被ADP占据。这个位点可能是非催化位点，因为在30% Me2SO中结合在那里的核苷酸不会转化为ATP。F1在Me2SO中合成的ATP源自内源性结合的ADP。我们得出结论，30% Me2SO会影响该酶的腺嘌呤核苷酸结合特性。并讨论了其在促进ADP和磷酸盐形成ATP过程中的作用。
