Kozutsumi Y, Kawano T, Yamakawa T, Suzuki A
Department of Membrane Biochemistry, Tokyo Metropolitan Institute of Medical Science.
J Biochem. 1990 Nov;108(5):704-6. doi: 10.1093/oxfordjournals.jbchem.a123268.
The activity of CMP-N-acetylneuraminic acid hydroxylase, that converts CMP-N-acetylneuraminic acid (CMP-NeuAc) to CPM-N-glycolylneuraminic acid (CMP-NeuGc), in mouse liver was determined by a newly developed HPLC method using non-radioactive CMP-NeuAc as a substrate. The activity was detected in the cytosol fraction but not in the microsomal fraction. Either NADH or NADPH was used as an electron donor by the cytosol enzyme, but NADH was much more efficiently used than NADPH. An antibody against cytochrome b5 markedly reduced the CMP-NeuAc hydroxylase activity when added to incubation mixture containing either NADH or NADPH as an electron donor. These data led us to postulate the following electron transport system, which is involved in the CMP-NeuAc hydroxylation in mouse liver cytosol: (formula; see text) where X, Y, and Z are components supposedly involved.
采用一种新开发的以非放射性CMP - N - 乙酰神经氨酸（CMP - NeuAc）为底物的高效液相色谱法，测定了小鼠肝脏中CMP - N - 乙酰神经氨酸羟化酶（该酶将CMP - N - 乙酰神经氨酸（CMP - NeuAc）转化为CMP - N - 羟乙酰神经氨酸（CMP - NeuGc））的活性。在胞质溶胶组分中检测到了该活性，但微粒体组分中未检测到。胞质溶胶酶以NADH或NADPH作为电子供体，但NADH比NADPH的利用效率高得多。当向含有NADH或NADPH作为电子供体的孵育混合物中添加抗细胞色素b5抗体时，该抗体显著降低了CMP - NeuAc羟化酶的活性。这些数据使我们推测出以下参与小鼠肝脏胞质溶胶中CMP - NeuAc羟基化的电子传递系统：（公式；见正文）其中X、Y和Z是可能涉及的组分。
