Molecular evidence for the involvement of alpha crystallin in the colouration/crosslinking of crystallins in age-related nuclear cataract

Chen, YC; Reid, GE; Simpson, RJ; Truscott, RJW

Author(s): Chen, YC; Reid, GE; Simpson, RJ; Truscott, RJW;
Details: Publication Year 1997-12,Volume 65,Issue #6,Page 835-840
Journal Title: EXPERIMENTAL EYE RESEARCH
Publication Type: Journal Article
Abstract: The proteins of the lens which become insoluble, crosslinked and coloured as a result of the onset of human nuclear cataract have been studied using a combination of enzymatic digestion and HPLC/mass spectrometry (MS). The objective was to determine if such an approach could provide information on the identities of the polypeptide components involved in the colouration and crosslinking and to discover whether any crystallins predominate in this characteristic post-translational modification process. Initially, coloured high molecular weight peptides were isolated from a tryptic/chymotryptic digest of the 6M guanidine hydrochloride-insoluble lens protein fraction. These tryptic/chymotryptic peptides were then incubated with pronase and the small peptides released, purified by gel filtration. All but one of the peptides analysed by HPLC/MS/MS were found to contain proline. Peptides derived from alpha-crystallin were found to comprise the great majority of the peptides characterised. No gamma-crystallin peptides were observed. Both alpha A-crystallin and alpha B-crystallin were represented. Further, all but one of these peptides were derived from the N-terminal region of the alpha-crystallin subunits: a region recently implicated in the chaperone activity of alpha-crystallin. This finding suggests that the putative N-terminal domain of alpha-crystallin may be involved at the molecular level in the process of crosslinking and colouration which is known to be characteristic of age-related nuclear cataract. It is, therefore, conceivable that an early stage of these cataractous modifications may involve alpha-crystallin acting as a molecular chaperone. (C) 1997 Academic Press Limited.
Publisher: ACADEMIC PRESS LTD
Keywords: HUMAN LENS PROTEINS; IDENTIFICATION; PEPTIDES; CHAPERONE; CYSTEINE; ACID
Publisher's Version: https://doi.org/10.1006/exer.1997.0393
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 1997-12-01 12:00:00