title: Specific glutamine and asparagine residues of gamma-S crystallin are resistant to in vivo deamidation.
abstract: It has been hypothesized that resistance to nonenzymatic deamidation of asparagine and glutamine residues may be an important determinant of protein stability in vivo. As a test of this hypothesis, we analyzed the central region of old human lenses, which contain proteins such as gamma-S crystallin that were synthesized during the fetal-embryonic periods of development. Total protein from the fetal-embryonic region of old human lenses was digested with trypsin, followed by resolution of tryptic fragments containing amidated and deamidated forms using high pressure liquid chromatography-reverse phase chromatography together with synthetic peptide standards and mass spectral analysis. The results demonstrate no detectable deamidation of glutamine 92, glutamine 96, asparagine 143, and glutamine 170 from gamma-S crystallin from old human lenses, consistent with the hypothesis that very long-lived proteins can contain asparagine and glutamine residues that are extremely resistant to in vivo deamidation.
authors.affiliation: Division of Biology, Ackert Hall, Kansas State University, Manhattan, Kansas 66506, USA. takemlj@ksu.edu
authors.forename: L
authors.initials: L
authors.lastname: Takemoto
authors.forename: D
authors.initials: D
authors.lastname: Boyle
mesh_terms: D000368:Aged; D000595:Amino Acid Sequence; D001216:Asparagine / Q000378:metabolism*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003459:Crystallins / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping; D013329:Structure-Activity Relationship
chemical_list: D003459:Crystallins; D005973:Glutamine; D001216:Asparagine