Mortensen H B, Christophersen C
Clin Chim Acta. 1983 Nov 15;134(3):317-26. doi: 10.1016/0009-8981(83)90370-4.
We examined the stability of the ketoamine adduct, termed HbA1c, formed between the N-terminal valine of the haemoglobin A (HbA) beta chain and D-glucose using an isoelectric focusing method. Prolonged saline incubation of purified HbA1c followed by renewed isoelectric focusing revealed that the HbA1c concentration decreased while a corresponding increase in the HbA concentration occurred. The emergence of haemoglobin A on saline incubation indicates that the non-enzymatic glucosylation of haemoglobin A to HbA1c is a reversible process. This finding was further substantiated by kinetic studies on the formation and breakdown of the ketoamine adduct during incubation of red cells in glucose and saline. It appeared that the rate constant for the formation k2 was 14.2 X 10(-6) X s-1 at 37 degrees C while the rate constant for dissociation k-2 was 1.7 X 10(-6) X s-1. From these data an equilibrium constant K of 8.4 was calculated. This information should be of importance in interpretation of HbA1c levels during abrupt changes in diabetic control.
我们使用等电聚焦法研究了血红蛋白A（HbA）β链的N端缬氨酸与D-葡萄糖之间形成的酮胺加合物（称为HbA1c）的稳定性。对纯化的HbA1c进行长时间盐水孵育，然后重新进行等电聚焦，结果显示HbA1c浓度降低，同时HbA浓度相应增加。盐水孵育时出现血红蛋白A表明血红蛋白A非酶糖基化为HbA1c是一个可逆过程。红细胞在葡萄糖和盐水中孵育期间对酮胺加合物形成和分解的动力学研究进一步证实了这一发现。在37℃时，形成速率常数k2似乎为14.2×10^(-6)×s^(-1)，而解离速率常数k-2为1.7×10^(-6)×s^(-1)。根据这些数据计算出平衡常数K为8.4。该信息对于解释糖尿病控制突然变化期间的HbA1c水平应具有重要意义。
