Wang Y, Obungu V, Beattie D S
Department of Biochemistry, West Virginia University School of Medicine, Morgantown 26505-9142, USA.
Arch Biochem Biophys. 1998 Apr 15;352(2):193-8. doi: 10.1006/abbi.1998.0590.
In recent studies we reported that dicyclohexylcarbodiimide (DCCD) inhibited proton translocation in ubiquinol:cytochrome c oxidoreductase (cytochrome bc1 complex) from yeast mitochondria where it was bound to aspartate-160 of cytochrome b. In the current study, we report that DCCD and its fluorescent analogue, N-cyclohexyl-N'-[4-(dimethylamino)naphthyl]-carbodiimide (NCD-4), inhibit 50-60% proton pumping in the cytochrome bc1 complex of the bacterium Rhodobacter sphaeroides with a 20% inhibition of electron transfer activity. Radioactive DCCD is bound exclusively to cytochrome b at aspartate-187, which is located at the C-terminal region of the CD loop connecting membrane-spanning helices C and D of cytochrome b. Fluorescent studies with NCD-4 revealed that aspartate-187 is located in a mildly hydrophobic pocket in the bc1 complex at a distance of 2-3 A from the surface of the membrane.
在最近的研究中我们报道，二环己基碳二亚胺（DCCD）抑制酵母线粒体中泛醇：细胞色素c氧化还原酶（细胞色素bc1复合体）中的质子转运，它与细胞色素b的天冬氨酸-160结合。在当前研究中，我们报道DCCD及其荧光类似物N-环己基-N'-[4-(二甲基氨基)萘基]碳二亚胺（NCD-4）抑制球形红杆菌细胞色素bc1复合体中50%-60%的质子泵浦，同时对电子传递活性有20%的抑制。放射性DCCD仅与细胞色素b的天冬氨酸-187结合，该位点位于连接细胞色素b跨膜螺旋C和D的CD环的C末端区域。用NCD-4进行的荧光研究表明，天冬氨酸-187位于bc1复合体中一个轻度疏水的口袋中，距离膜表面2-3埃。
