1983 Volume 26 Issue 8 Pages 845-852
The non-enzymatic glycosylation rates of serum proteins, hemoglobin and lens proteins were determined. In addition, in vitro studies on the non-enzymatic glycosylation of serum proteins and lens proteins were performed with various concentrations of D-glucose.
1) The glycosylated serum protein (GSP) levels were determined by thiobarbituric acid assay after removing free glucose by pretreatment with trichloroacetic acid.The GSP levels in 93 diabetics were 1.00±0.19 5-hydroxymethylfurfural (5-HMF) nmolcs/mg protein (mean±SD).This value was significantly higher (p<0.001) than that in normals (0.75±0.085-HMF nmoles/mg protein).The glycosylated hemoglobin A1 (HbA1) levels were also determincd with a Corning HbA1 kit.
2) The correlation between the GSP or HbA1 level and blood sugar control was examined.The highest correlation was obtained between the GSP level and mean fasting blood sugar (FBS) level from 1 to 3 weeks previously (r=0.641, p<0.001) and also between the HbAi level and mean FBS level from 1 to 3 months previously (r=0.0.748, p<0.001).
3) The glycosylation rates of soluble lens proteins (6, 500×gsupernatant in0.05M sodium phosphate buffer, pH 7.2) were determined using cataractous lenses extracted from senile and diabetic subjects.The glycosylated lens protein (GLP) levels were 0.79±0.23 and 1.64±0.43 5-HMF nmoles/mg protein in senile and diabetic cataracts, respectively.The latter value was significantly higher (p×0.001) than the former, while the mean age of diabetics (66.3 y) was significantly lower than the senile one (75.4 y).
4) The in vitro non-enzymatic glycosylation of serum proteins and lens proteins was dependent on glucose concentration and incubation time.
5) Based on the present results, it is suggested that a hyperglycemic state in diabetics can accelerate the non-enzymatic glycosylation of various body proteins, and that measurement of the glycosylation rates of body proteins may represent a valuable means of assessing blood sugar control and investigating some aspects of the pathophysiology of diabetic complications.
