Yoshimoto M, Kusunose E, Yamamoto S, Maekawa M, Kusunose M
Biochem Int. 1986 Nov;13(5):749-55.
Two forms of cytochrome P-450 (P-450), designated P-450 k-1 and P-450 k-2, have been purified about 100-fold from rat kidney cortex microsomes. P-450 k-1 and P-450 k-2 have monomeric molecular weights of 51,500 and 52,000, respectively, on sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis. Absolute spectra of the oxidized forms indicate that P-450 k-1 is largely in the low-spin state and partly in the high-spin state, and that P-450 k-2 is essentially all in the former. The absorption maxima in reduced carbon monoxide difference spectra are at 450.5 and 451 nm with P-450 k-1 and P-450 k-2, respectively. The two P-450s catalyze the omega- and (omega-1)-hydroxylation of fatty acids such as caprate, laurate, myristate, and palmitate, although P-450 k-1 exhibits a higher specific activity with all fatty acids tested. In addition, P-450 k-1 is capable of hydroxylating prostaglandin (PG) A1 and A2 at the omega-position, whereas P-450 k-2 has no activity toward PGs. These activities are all stimulated by addition of cytochrome b5. The two P-450s give different peptide map patterns when partially digested with Staphylococcus aureus V8 protease or papain.
已从大鼠肾皮质微粒体中纯化出两种细胞色素P-450（P-450），分别命名为P-450 k-1和P-450 k-2，纯化倍数约为100倍。在十二烷基硫酸钠（SDS）-聚丙烯酰胺凝胶电泳中，P-450 k-1和P-450 k-2的单体分子量分别为51,500和52,000。氧化形式的绝对光谱表明，P-450 k-1主要处于低自旋状态，部分处于高自旋状态，而P-450 k-2基本上全部处于前一种状态。还原型一氧化碳差光谱中的吸收最大值，P-450 k-1和P-450 k-2分别在450.5和451 nm处。这两种P-450可催化癸酸、月桂酸、肉豆蔻酸和棕榈酸等脂肪酸的ω-和（ω-1）-羟基化反应，不过P-450 k-1对所有测试脂肪酸的比活性更高。此外，P-450 k-1能够将前列腺素（PG）A1和A2在ω-位羟基化，而P-450 k-2对PGs无活性。添加细胞色素b5会刺激所有这些活性。用金黄色葡萄球菌V8蛋白酶或木瓜蛋白酶部分消化时，这两种P-450呈现出不同的肽图谱模式。
