The effect of α, β_H, β_L and γ_s crystallins on the inhibition of oxidative dimerization of γβ crystallin

Purpose. To examine the role of various lens crystallins in the inhibition of the oxidative dimerization of yB or (y//) crystallin. Methods. 200/i£ each of four solutions containing mixtures of (1) Buffer + γII, (2) β_High + γ II (3) β_Lau + γ II and (4) γs+γII crystallins were incubated at room temperature in 0.1M sodium phosphate buffer, pH 7.1. The ratios (mole/mole) of β and βi to γII were 2:1, while that of γ_s to γII was 1:1. The amount of γII in each solution was held constant at 100 mg/ml. For each of these solutions, we determined as a function of time by HPLC, the percentage of dimers formed by oxidation. We also measured the phase separation temperature, Tph, as a function of time for -300 hrs. Results. We found that in addition to a crystallin1, βHlβL and ys crystallins are also potent inhibitors of yII dimerization. Indeed, ys appears to be a much more effective inhibitor of dimers than a crystallin. We also find dramatic suppression of Tpft, in the solutions containing a, βn,βi and ys crystallins. Conclusions. 1) the oxidative dimerization of y II crystallin is suppressed not only by a crystallin, but also by βn>βi d y$ crystallins. 2) the observation that ys is a more efficient inhibitor of aggregation in y II crystallin, suggests a special role for the differential synthesis of ys in the lens. 1 Pande, J., Alexander, K., Ogun, O. and Benedek, G. (1996) Invest. Ophthalmol. Vis. Sei. 37, S443.