Abstract
In order to examine how the structures of α- and β-crystallins, the main proteins of lens cortex, change with pH, spectrophotometric titration of thyrosin group, considered to play an important part in the steric configuration of these proteins, was carried out in solutions of various ionic strengths (KCl), at 297 mμ. The titration curves were simple S-shape in both proteins, dissociation of thyrosin group in the proteins was the same, and hardly any difference was observed between the two proteins in dissociation characteristics. In the titration, however, some time-dependency was observed in β-crystallin regarding changes in absorbance, although such dependency was not observed in a-crystallin. The same result was obtained in 8M urea solution, indicating that β-crystallin has a structure less liable to undergo decoiling than α-crystallin. Dissociation of thyrosin group in both proteins was found to be unaffected by other dissociating groups or presence of potassium chloride, under any conditions.
