Bonomi F, Long R C, Kurtz D M
Department of Chemistry, University of Georgia, Athens 30602.
Biochim Biophys Acta. 1989 Nov 30;999(2):147-56. doi: 10.1016/0167-4838(89)90211-2.
The purification to homogeneity of the membrane-bound NADH-cytochrome-b5 reductase from erythrocytes of the sipunculid, Phascolopsis gouldii is reported. This highly purified reductase has allowed more detailed characterizations of its molecular and kinetic properties than was possible in a previous study (Utecht, R.E. and Kurtz, D.M., Jr. (1988) Biochim. Biophys. Acta 953, 164-178). The reductase has a molecular weight of 34,000 and contains FAD as the prosthetic group. In aqueous solution containing 0.5 vol% Triton X-100, the reductase forms an aggregate of Mr approximately 220,000. A higher purity preparation of P. gouldii erythrocyte b5 was also obtained. The combination of purified, solubilized reductase and cytochrome b5 was shown to catalyze the quantitative two-electron reduction of [Fe(III),Fe(III)]methemerythrin to [Fe(II),Fe(II)]deoxyhemerythrin by NADH. The P. gouldii NADH-cytochrome b5 reductase is the first from hemerythrin-containing erythrocytes to be purified and characterized. This methemerythrin reduction system appears to be analogous to methemoglobin reductases from vertebrate erythrocytes.
报道了从星虫类动物古氏管体星虫（Phascolopsis gouldii）红细胞中纯化得到膜结合NADH-细胞色素b5还原酶并使其达到同质的过程。与之前的研究（Utecht, R.E.和Kurtz, D.M., Jr.（1988年）《生物化学与生物物理学报》953卷，第164 - 178页）相比，这种高度纯化的还原酶使得对其分子和动力学特性进行更详细的表征成为可能。该还原酶分子量为34,000，含有FAD作为辅基。在含有0.5体积% Triton X - 100的水溶液中，该还原酶形成分子量约为220,000的聚集体。还获得了更高纯度的古氏管体星虫红细胞b5制剂。纯化的、可溶的还原酶与细胞色素b5的组合被证明能催化NADH将[Fe(III),Fe(III)]高铁血绿蛋白定量地双电子还原为[Fe(II),Fe(II)]脱氧血绿蛋白。古氏管体星虫NADH-细胞色素b5还原酶是首个从含血绿蛋白的红细胞中纯化并表征的此类还原酶。这种高铁血绿蛋白还原系统似乎类似于脊椎动物红细胞中的高铁血红蛋白还原酶。
