Ota I M, Gilbert J M, Clarke S
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Biochem Biophys Res Commun. 1988 Mar 30;151(3):1136-43. doi: 10.1016/s0006-291x(88)80484-4.
We have been able to separate protein carboxyl methyltransferase activity from human erythrocyte cytosol into two major fractions by DEAE-cellulose chromatography. These isozymes, designated I and II, are characterized by their isoelectric points of approximately 6.6 and 5.5 as determined by isoelectric focusing in polyacrylamide gels. The ratio of the isozymes (II/I) was found to range from 0.52 to 1.2 in blood samples from 14 individuals. We did not detect differences in this ratio between males and females. We also found no differences between freshly drawn and outdated blood samples. Both isozymes catalyzed the methylation of proteins such as ovalbumin as well as synthetic L-isoaspartyl-containing peptides.
我们已通过二乙氨基乙基纤维素色谱法，将人红细胞胞质溶胶中的蛋白质羧基甲基转移酶活性分离成两个主要部分。这些同工酶分别命名为I和II，通过在聚丙烯酰胺凝胶中进行等电聚焦测定，其等电点约为6.6和5.5。在14名个体的血样中，同工酶比例（II/I）在0.52至1.2之间。我们未检测到男性和女性在该比例上的差异。我们还发现新鲜抽取的血样和过期血样之间没有差异。两种同工酶都催化蛋白质（如卵清蛋白）以及合成的含L-异天冬氨酸肽的甲基化。
