Morino H, Kawamoto T, Miyake M, Kakimoto Y
J Neurochem. 1987 Apr;48(4):1201-8. doi: 10.1111/j.1471-4159.1987.tb05647.x.
A S-adenosylmethionine:protein-lysine N-methyltransferase (EC 2.1.1.43) has been purified from rat brain cytosol 7,080-fold with a yield of 8%, using octopus calmodulin as a substrate. It contains a lysine residue that is not fully methylated. The enzyme was purified by ammonium sulfate fractionation, Sephacryl S-200 gel filtration, and phosphocellulose and octopus calmodulin-Sepharose affinity chromatographies. Among protein substrates, it was highly specific toward octupus calmodulin. The Km values for octopus calmodulin and S-adenosyl-L-methionine were found to be 2.2 X 10(-8) M and 0.8 X 10(-6) M, respectively. The molecular weight was estimated to be 57,000 by gel filtration and the pH optimum was between 7.5 and 8.5. The enzyme was stimulated in the presence of 10(-7) M Mn2+ and 10(-4) M Ca2+. HPLC of the acid hydrolysate of methyl-3H-labeled calmodulin showed the formation of epsilon-N-mono, epsilon-N-di, and epsilon-N-trimethyllysine. Reverse-phase HPLC of tryptic peptides of the methyl-3H-labeled calmodulin demonstrated that the labeled N-methyllysine lies in the 107-126 peptide. These findings suggest that this enzyme methylated a specific lysine residue of octopus calmodulin.
一种S-腺苷甲硫氨酸：蛋白质赖氨酸N-甲基转移酶（EC 2.1.1.43）已从大鼠脑细胞质中以8%的产率纯化了7080倍，使用章鱼钙调蛋白作为底物。它含有一个未完全甲基化的赖氨酸残基。该酶通过硫酸铵分级分离、Sephacryl S-200凝胶过滤以及磷酸纤维素和章鱼钙调蛋白-琼脂糖亲和色谱法进行纯化。在蛋白质底物中，它对章鱼钙调蛋白具有高度特异性。发现章鱼钙调蛋白和S-腺苷-L-甲硫氨酸的Km值分别为2.2×10^(-8) M和0.8×10^(-6) M。通过凝胶过滤估计分子量为57,000，最适pH在7.5至8.5之间。该酶在10^(-7) M Mn2+和10^(-4) M Ca2+存在下受到刺激。对甲基-3H标记的钙调蛋白酸水解产物进行高效液相色谱分析显示形成了ε-N-单甲基、ε-N-二甲基和ε-N-三甲基赖氨酸。对甲基-3H标记的钙调蛋白胰蛋白酶肽段进行反相高效液相色谱分析表明，标记的N-甲基赖氨酸位于107 - 126肽段中。这些发现表明该酶使章鱼钙调蛋白的一个特定赖氨酸残基发生甲基化。
