2-D electrophoresis distribution of stable 14C-glycation products from pig lens crystallins in relation to diabetic cataract formation.
We incubated pig lens crystallins with 14C-glucose and eliminated the unstable glycation products with posterior dialysis. All five soluble protein classes separable by Sepharose CL-6B column chromatography were radioactive, but the alpha-H fraction was five times more so than any of the others (14.2 vs. 3.1, 3.2, 1.6, and 2.3 x 10(3) cpm/mg protein, for alpha-H, alpha-L, beta-H, beta-L, and gamma proteins, respectively). However, the autoradiographs of our two-dimensional electrophoresis patterns revealed glycosyl adducts in all the soluble protein subunits except for gamma-a, and showed no evidence of preferential glycation of the alpha-H fraction subunits. We conclude that stable glycation products find their way into the alpha-H fraction but that the components of this fraction do not undergo unusually extensive glycation. This is consistent with the theory that senile diabetic cataracts arise from the hyperaggregation of proteins due to glycation.
Vidal
P
P
Service of Endocrinology and Nutrition, Hospital General de Galicia, Clinico Universitario, University of Santiago, Santiago de Compostela, Spain.
Cabezas-Cerrato
J
J
D000818:Animals; D002250:Carbon Radioisotopes; D002386:Cataract / Q000209:etiology*; D003930:Diabetic Retinopathy / Q000209:etiology*; D015180:Electrophoresis, Gel, Two-Dimensional; D005947:Glucose / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis* / Q000302:isolation & purification; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism*; D008954:Models, Biological; D013552:Swine
D002250:Carbon Radioisotopes; D006023:Glycoproteins; D005947:Glucose