Kojima T, Hashimoto H, Tsukamoto H, Ito T, Ogawa K, Satake T
Second Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Cardiovasc Res. 1987 Jun;21(6):433-8. doi: 10.1093/cvr/21.6.433.
Subforms of creatine kinase MM isoenzyme (isoforms, pI: MMA = 7.95, MMB = 7.76, MMC = 7.54) in human myocardium and serum were quantified by chromatofocusing. Creatine kinase MMA was a dominant isoform (greater than 94% of MM) in normal (n = 3) and in both infarcted and non-infarcted myocardium (n = 2). To investigate isoform conversion in vitro partially purified MMA was incubated with human plasma at 37 degrees C for 24 h (n = 5). Creatine kinase MMB (0%, 47%, 44% of MM at 0, 12, 24 h respectively) and MMC (0%, 22%, 42%) sequentially appeared in incubation media whereas MMA (100%, 31%, 14%) disappeared rapidly with a mean disappearance rate of -0.00169(0.00021)(SD) min-1. Individual differences in conversion velocity were small (SD less than 5%). To investigate isoform conversion in vivo serum isoforms were analysed in patients with acute myocardial infarction (n = 7). MMA was first dominant (A:B:C = 54:34:12%) in the early stage (6-9 h after the onset of chest pain) followed by MMB dominant (19:42:39%) in the middle stage (24-35 h), and MMC dominant (6:22:72%) in the late stage (54-60 h). Changes in isoform proportion were time dependent regardless of serum creatine kinase activity. These findings are consistent with canine isoform conversion reported previously except that in man the velocity of conversion was slower than in the dog. Thus analysis of serum creatine kinase MM isoforms may allow the onset of acute myocardial infarction to be precisely dated. Moreover, determination of MMA, the isoform native to myocardium with a short serum half life, may be useful in the prompt diagnosis of myocardial infarction.
采用层析聚焦法对人心肌和血清中肌酸激酶MM同工酶的亚形式（同工型，pI：MMA = 7.95，MMB = 7.76，MMC = 7.54）进行定量分析。在正常心肌（n = 3）以及梗死和未梗死心肌（n = 2）中，肌酸激酶MMA均为主要同工型（占MM的94%以上）。为了研究体外同工型转换情况，将部分纯化的MMA与人血浆在37℃孵育24小时（n = 5）。孵育介质中依次出现了肌酸激酶MMB（在0、12、24小时时分别占MM的0%、47%、44%）和MMC（0%、22%、42%），而MMA（100%、31%、14%）迅速消失，平均消失速率为 -0.00169(0.00021)(标准差)分钟⁻¹。转换速度的个体差异较小（标准差小于5%）。为了研究体内同工型转换情况，对急性心肌梗死患者（n = 7）的血清同工型进行了分析。在早期（胸痛发作后6 - 9小时），MMA占主导（A:B:C = 54:34:12%），随后在中期（24 - 35小时）MMB占主导（19:42:39%），在后期（54 - 60小时）MMC占主导（6:22:72%）。同工型比例的变化与时间相关，与血清肌酸激酶活性无关。这些发现与先前报道的犬类同工型转换情况一致，只是在人类中转换速度比犬类慢。因此，分析血清肌酸激酶MM同工型可能有助于精确确定急性心肌梗死的发病时间。此外，测定心肌原生且血清半衰期较短的同工型MMA，可能有助于心肌梗死的快速诊断。
