Yoshida S, Yubisui T, Takeshita M
Arch Biochem Biophys. 1984 Jul;232(1):296-304. doi: 10.1016/0003-9861(84)90545-9.
Biochemical aspects of b-type cytochromes in swine cerebral microsomes were different from those of cytochrome b5 in liver microsomes, as well as the difference in absorption spectra. First, the kinetic constants, Km and Vmax, in rotenone-insensitive NADH-cytochrome c reductase activity were different from those of liver microsomes, and the activity of cerebral microsomes was higher than that of liver microsomes. Second, midpoint potentials (Em) of b-type cytochromes in cerebral microsomes were measured and compared with liver microsomal cytochrome b5. In cerebral microsomes two components of b-type cytochromes were resolved, and showed Em's of -30 and +50 mV, respectively, in the presence of 2 mM KCN. On the other hand, the Em of liver microsomal cytochrome b5 was -6 mV. The high-potential component of cerebral microsomal b-type cytochromes was identified as brain-b'5 [S. Yoshida, T. Yubisui, and M. Takeshita (1983) Biochem. Int. 7, 291-298] and the low-potential component as brain-b5. The significance of the difference between cerebral and liver microsomal b-type cytochromes was discussed.
猪脑微粒体中b型细胞色素的生化特性与肝微粒体中的细胞色素b5不同，吸收光谱也存在差异。首先，鱼藤酮不敏感的NADH-细胞色素c还原酶活性的动力学常数Km和Vmax与肝微粒体不同，脑微粒体的活性高于肝微粒体。其次，测量了脑微粒体中b型细胞色素的中点电位（Em），并与肝微粒体细胞色素b5进行比较。在脑微粒体中，b型细胞色素的两个组分被分辨出来，在2 mM KCN存在下，其Em分别为-30和+50 mV。另一方面，肝微粒体细胞色素b5的Em为-6 mV。脑微粒体b型细胞色素的高电位组分被鉴定为脑-b'5 [S. Yoshida, T. Yubisui, and M. Takeshita (1983) Biochem. Int. 7, 291-298]，低电位组分被鉴定为脑-b5。文中讨论了脑和肝微粒体b型细胞色素差异的意义。
