In vitro glycation and acetylation (by aspirin) of rat crystallins.
In vitro studies with rat lens crystallins were conducted to explore the mechanism by which aspirin (ASA-acetylsalicylic acid) could inhibit cataractogenesis. The purpose of the present study is to show whether gamma-crystallin is the primary target for glycation by glucose and acetylation by ASA. Lens soluble fractions from one and seven month old Sprague-Dawley rats were incubated with 5 mM [14C]glucose with and without 10 mM ASA. alpha, beta, and gamma-crystallins were separated by molecular sieve HPLC and specific activities of each crystallin determined. In vitro acetylation was also studied by measuring protein bound [14C]acetyl groups after incubation with [14C]acetyl ASA. There was 2 to 4-fold faster glycation of gamma-crystallin than all other crystallins from 1-month-old rats and ASA inhibited glycation of gamma-crystallin four times more than that of alpha and beta-crystallins, thus showing preferential glycation of gamma-crystallin and its selective inhibition by ASA. [14C]acetyl incorporation showed increased acetylation of gamma-crystallin in one month old rats, whereas in older lenses acetylation of other crystallins predominated. Treatment with 10 mM ASA showed 35% decrease in free -NH2 groups but protein thiols remained unchanged.
Dept. of Biochemistry & Molecular Biology, Medical College of Georgia, Augusta 30912.
M
M
Cherian
E C
EC
Abraham
D000107:Acetylation / Q000187:drug effects; D000588:Amines / Q000032:analysis; D000818:Animals; D001241:Aspirin / Q000378:metabolism / Q000494:pharmacology*; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D003459:Crystallins / Q000187:drug effects* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D006031:Glycosylation / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013438:Sulfhydryl Compounds / Q000032:analysis
D000588:Amines; D002250:Carbon Radioisotopes; D003459:Crystallins; D013438:Sulfhydryl Compounds; D005947:Glucose; D001241:Aspirin