Spectroscopic study on the effects of nonenzymatic glycation in human alpha-crystallin.
Nonenzymatic glycated lens alpha-crystallin, isolated from human diabetic cataract lenses, does not differ in subunit size and secondary structure from nonglycated alpha-crystallin. The tertiary structure, however, has undergone a significant change as reflected in the changes of near-ultraviolet (UV) circular dichroism (CD) and fluorescence of intrinsic probes (tryptophan, nontryptophan) and extrinsic probes [(MIANS (6-(4'-maleimidylanilino)naphthalene-2-sulfonic acid) and TNS (6-(p-toluidinyl)naphthalene-2-sulfonate)]. A decrease in tryptophan fluorescence and an increase in nontryptophan fluorescence were observed for glycated alpha-crystallin. Decreased intensities of SH-specific fluorescent probes (MIANS) and hydrophobic probe (TNS) also were observed. The near UV CD and TNS polarization results suggest a more unfolded structure of the glycated crystallin. The significant decrease of sulfhydryl groups in glycated protein suggests that glycation facilitates a further secondary change.
D000368:Aged; D000369:Aged, 80 and over; D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D002386:Cataract / Q000209:etiology / Q000378:metabolism*; D002942:Circular Dichroism; D003459:Crystallins / Q000378:metabolism*; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000378:metabolism*; D005470:Fluorometry; D005947:Glucose / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007904:Lens Cortex, Crystalline / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism*; D009282:Naphthalenesulfonates / Q000378:metabolism; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D013053:Spectrophotometry; D014364:Tryptophan / Q000378:metabolism
D000817:Anilino Naphthalenesulfonates; D003459:Crystallins; D009282:Naphthalenesulfonates; C021310:2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid; C009497:2-(4-toluidino)-6-naphthalenesulfonic acid; D014364:Tryptophan; D005947:Glucose