Acetylation of lens crystallins: A possible mechanism by which aspirin could prevent cataract formation

The calf eye lens homogenate incubated with [1- 14C-acetyl] aspirin and separated into HMW, α, β H, β L and γ-crystallins by means of Sepharose 6B and Bio-Gel P2 columns showed radioactivity in all the crystallins. In contrast, no radioactivity was found in the crystallins when the lens homogenate was incubated with [ 14C-carboxyl] aspirin. These experiments clearly indicated that the eye lens crystallins are acetylated with aspirin. Furthermore, no decrease in the radioactivity in the crystallins after exhaustive dialysis against 0.15M NaCl suggests a covalent type of binding of acetyl moiety of aspirin to the lens crystallins. The significant decrease in the free ε-amino groups of aspirin-treated crystallins further suggests the probable sites of acetylation in the crystallins. It may be concluded that acetylation of free ε-amino groups of lens crystallins by aspirin may confer protection against crystallin aggregation in cataractogenesis.