EFFECTS OF TEMPERATURE, CONCENTRATION AND CARBOXYMETHYLATION ON INTERACTIONS OF CALF LENS CRYSTALLINS

Concentration and temperature dependent interactions of calf cortical crystallins were studied by means of gel filtration and disc gel electrophoretic analyses. Low temperature (8°C) gel filtration of either low or high levels of cortical crystallin extracts (5-59 A280 units) yields elution profiles that are indistinguishable in the distributions of α-, βH-, βL- and γ-crystallins. Gel filtration of low levels of extracts between 22 and 44°C causes a gradual but ultimately complete temperature-dependent disappearance of the region of βH-crystallins and to a lesser degree in the γ-crystallin peak. Chromatography of high levels of extracts at 44°C results in the reappearance of a high mol. wt. β-crystallin peak with electrophoretic property and polypeptide composition different from those of βH-crystallin isolated at the low temperature of 8°C. Preincubation of high levels of extracts at 44°C causes some small but irreversible changes in the elution profile obtained at 8°C. Taken together these results suggest that the presence of high mol. wt. β-crystallin is the result of largely reversible equilibria between β-crystallins and other lenticular components. The reaction of calf cortical extracts with increasing amounts of iodoacetic acid results in a progressive loss in the βH-crystallin region of the 8°C filtration profile. Results from amino acid analyses and sodium dodecylsulfate (SDS) gel electrophoreses of the respective α-, βL- and γ-crystallin fractions indicate that the SH moieties of the cysteine residues are essential to the formation of high mol. wt. β-crystallins. © 1979.