DIRECT APPROACH TO IDENTIFICATION, AT THE MOLECULAR-LEVEL, OF MODIFIED PROTEINS IN HUMAN NUCLEAR CATARACTOUS LENSES - BETA-CRYSTALLIN IS A COMPONENT OF THE UREA-INSOLUBLE PROTEIN-FRACTION
RAJ OHAIR, MM SHEIL, RJW TRUSCOTT
Ophthalmic Research | KARGER | Published : 1992
In an effort to elucidate the molecular changes which take place in the human lens with the onset of nuclear cataract, the urea-insoluble protein fraction, solubilized with dithiothreitol, was digested with trypsin. Tryptic peptides separated by HPLC, were examined by both mass spectrometry and Edman degradation. A pentapeptide Gly-Glu-Tyr-Pro-Arg which is contained within the beta-crystallin sequence was isolated. This finding provides direct evidence that beta-crystallin is present in the urea-insoluble protein fraction which is known to be characteristic of human nuclear cataract lenses.