HYDRATION PROPERTIES OF LENS CRYSTALLINS

The water binding properties of bovine lens crystallins, α, βH, βL and low molecular weight (LMW), were investigated with different techniques. The water sorptive capacity was obtained in high vacuum sorption experiments volumetrically, and also gravimetrically in controlled atmosphere experiments. The two methods gave reproducible isotherms. The strongly sorbed water (bound water) was evaluated from the B.E.T. monolayer and from the values of isosteric heats. The bound water content of the crystallins were also measured by combined differential scanning calorimetry and thermogravimetric analysis. The non-freezable water contents calculated as % of the total water content and also as g g-1 crystallin, were used as an indicator for bound water. In all thre different techniques, the following order was obtained: βH > α > βL - LMW. © 1990.