[Studies on human gamma-crystallins. I. Quantitative changes with age and cataract formation]

Water soluble protein from human lenses at various ages are separated by Sephadex gel chromatography. The results show that there are major three gamma-crystallins (gamma 1, gamma 2, gamma 3) in human lenses. In normal lenses the total contents of the three gamma-crystallins in water soluble fraction of lens proteins keep stable as age increases. However, among the three gamma-crystallins, gamma 1 increase and gamma 2 decrease markedly, and very little change with gamma 3 are found as age increases. In nuclear cataractous lenses, all three gamma-crystallins decrease as compared with the normal lenses of the same age. The variety of synthesis of each gamma-crystallin is mainly responsible for the changes of their quantities. It is postulated that the total low molecular weight crystallin contents in water soluble proteins of the human lens is related to the transparency of lens. The structural characterization of gamma 3-crystallin is responsible for the relative constant as age increases.