Intrapolypeptide disulfides in human alphaA-crystallin and their effect on chaperone-like function.
We report studies on the role of protein-protein disulfides (PSSP) in the age-related loss of chaperone activity of alpha-crystallins. AlphaL-crystallin fraction was isolated from human lenses of different ages and the chaperone-like activity was determined before and after treatment with glutathione reductase (GR) and NADPH. The results confirmed an age-dependent decrease in chaperone-like function and significant improvement of this function by GR treatment. Electrospray ionization mass spectrometric (ESIMS) analysis of alphaA-crystallin suggested the presence of very little protein-glutathione mixed disulfides. ESIMS analysis of Asp-N digests of alphaA-crystallin revealed that nearly all the remaining portion of Cys-131 and Cys-142 of alphaA-crystallin was present in the form of intrapolypeptide disulfide bonds. These results show for the first time that predominantly disulfide bonds formed during aging contribute to the age-dependent loss in chaperone activity of alpha-crystallin in human lenses.
Cherian-Shaw
M
M
Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912-2100, USA.
Smith
J B
JB
Jiang
X Y
XY
Abraham
E C
EC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000595:Amino Acid Sequence; D002648:Child; D003459:Crystallins / Q000737:chemistry* / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D005980:Glutathione Reductase / Q000378:metabolism; D006801:Humans; D007908:Lens, Crystalline / Q000737:chemistry / Q000502:physiology; D013058:Mass Spectrometry / Q000379:methods; D008875:Middle Aged; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship
D003459:Crystallins; D004220:Disulfides; D018832:Molecular Chaperones; D005980:Glutathione Reductase; D003545:Cysteine