Nochumson S, Durban E, Kim S, Paik W K
Biochem J. 1977 Jul 1;165(1):11-8. doi: 10.1042/bj1650011.
A protein methylase III responsible for specifically methylating the cytochrome c in Neurospora crassa was partially characterized by using unmethylated horse heart cytochrome c as a substrate. This enzyme utilizes S-adenosyl-L-methionine as the methyl donor. An analysis of the distribution of [14C]methyl groups in the peptides obtained by chymotrypsin digestion of the enzymically methylated cytochrome c showed that all of the radioactivity could be recovered within a single peak after chromatography. This indicates that the enzyme methylates a specific amino acid sequence within cytochrome c. On hydrolysis of the radioactive chymotryptic peptide, Me-14C-labelled epsilon -N-mono-methyl-lysine, epsilon-N-dimethyl-lysine and epsilon-N-trimethyl-lysine were identified. The enzyme can easily be extracted from the N. crassa mycelial pads and was purified approx. 30-fold.
通过使用未甲基化的马心血红素c作为底物，对粗糙脉孢菌中负责特异性甲基化细胞色素c的蛋白甲基化酶III进行了部分特性鉴定。该酶利用S-腺苷-L-甲硫氨酸作为甲基供体。对经酶促甲基化的细胞色素c经胰凝乳蛋白酶消化得到的肽段中[14C]甲基基团分布的分析表明，色谱分离后所有放射性都可在一个单一峰中回收。这表明该酶使细胞色素c内的特定氨基酸序列甲基化。对放射性胰凝乳蛋白酶肽段进行水解后，鉴定出了Me-14C标记的ε-N-单甲基赖氨酸、ε-N-二甲基赖氨酸和ε-N-三甲基赖氨酸。该酶很容易从粗糙脉孢菌菌丝垫中提取出来，并被纯化了约30倍。
