Austin G E, Mullins R H, Morin L G
Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
Clin Chem. 1987 Dec;33(12):2220-4.
Diabetic patients in poor glycemic control show increased glycation of total plasma proteins, but little is yet known about the relative extents to which the various individual proteins are glycated. Thus, we studied the non-enzymic glycation of several major plasma proteins and plasma protein fractions in normal and diabetic patients. In vivo glycation for most plasma proteins was very low in non-diabetic patients, only gamma globulin showing more than 5% glycation. In diabetic plasmas, glycation was much greater, immunoglobulins again showing the greatest proportion, followed in descending order by albumin, complement C3, fibrinogen, transferrin, haptoglobin, and alpha-1-antitrypsin. When plasma proteins were glycated in vitro, this order was IgG greater than complement C3 greater than albumin greater than transferrin greater than haptoglobin greater than alpha-1-antitrypsin. In general, proteins with the longest biological half-lives, such as IgG and albumin, showed the greatest in vivo glycation. On the other hand, proteins with high intrinsic glycability, such as complement C3, showed moderate glycation, despite a short half-life. Except for albumin, more basic proteins showed greater glycation than acidic proteins, but there was poor correlation between mole percent lysine and glycation. Evidently the relative extents of glycation of different plasma proteins are a complex function of integrated glucose concentrations over time and of the half-life and chemical characteristics of each protein.
血糖控制不佳的糖尿病患者血浆总蛋白的糖化作用增强，但对于各种单个蛋白糖化的相对程度，目前了解甚少。因此，我们研究了正常人和糖尿病患者几种主要血浆蛋白及血浆蛋白组分的非酶糖化作用。在非糖尿病患者中，大多数血浆蛋白的体内糖化作用非常低，只有γ球蛋白的糖化率超过5%。在糖尿病患者的血浆中，糖化作用要强得多，免疫球蛋白的糖化比例再次最高，其次依次是白蛋白、补体C3、纤维蛋白原、转铁蛋白、触珠蛋白和α-1抗胰蛋白酶。当血浆蛋白在体外进行糖化时，顺序为IgG＞补体C3＞白蛋白＞转铁蛋白＞触珠蛋白＞α-1抗胰蛋白酶。一般来说，生物半衰期最长的蛋白，如IgG和白蛋白，体内糖化作用最强。另一方面，内在糖化能力高的蛋白，如补体C3，尽管半衰期短，但糖化作用中等。除白蛋白外，碱性较强的蛋白比酸性蛋白的糖化作用更强，但赖氨酸摩尔百分比与糖化作用之间的相关性较差。显然，不同血浆蛋白糖化的相对程度是葡萄糖浓度随时间综合作用以及每种蛋白半衰期和化学特性的复杂函数。
