Morin L G
Clin Chem. 1977;23(4):646-52.
I determined the in vitro biological half-lives or decay constants for creatine kinase isoenzymes at various temperatures. Values at 37 degrees C are consistent with values reported by others in vivo, which suggests that in vivo irreversible inactivation is primarily thermal. Reversible inactivation appears to be an oxidation-reduction phenomenon. Proteins and some inactivators (urate, catecholamines) retard irreversible inactivation and preserve isoenzyme integrity. Dilution and thiols promote reversal of inactivity. Mercaptoethanol is the preferred thiol, particularly for storage and reactivation of isoenzyme MB. MB is sensitive to light and to freeze-thawing. I recommend that specimens be cooled promptly after drawing, that mercaptoethanol (10 mmol/liter) be added, and that they be stored refrigerated. Avoid prolonged exposure to light and freezing. A model of inactivation is proposed, which is based on the assumed existence of four monomer types: active, denatured, oxidized, and insulated. The model is consistent with dilution and thiol reactivation, lag phase variations, and subtype heterogeneity.
我测定了肌酸激酶同工酶在不同温度下的体外生物学半衰期或衰变常数。37摄氏度时的值与其他人在体内报道的值一致，这表明体内不可逆失活主要是由热引起的。可逆失活似乎是一种氧化还原现象。蛋白质和一些失活剂（尿酸盐、儿茶酚胺）可延缓不可逆失活并保持同工酶的完整性。稀释和硫醇可促进失活的逆转。巯基乙醇是首选的硫醇，特别是用于同工酶MB的储存和再激活。MB对光和冻融敏感。我建议采血后立即将标本冷却，加入巯基乙醇（10 mmol/升），并冷藏保存。避免长时间暴露于光和冷冻。提出了一种失活模型，该模型基于假定存在四种单体类型：活性型、变性型、氧化型和隔离型。该模型与稀释和硫醇再激活、滞后相变化以及亚型异质性一致。
