title: D-Amino acids in aged proteins: analysis and biological relevance.
abstract: Homochirality is essential for life. L-Amino acids are exclusively used as substrates for the polymerization and formation of peptides and proteins in living systems. However, d-amino acids, which are enantiomers of L-amino acids, were recently detected in various living organisms in the form of free D-amino acids and D-amino acid residues in peptides and proteins. In particular, D-aspartyl (Asp) residues have been detected in various proteins from diverse tissues of elderly individuals. Here, we describe three important aspects of our research: (i) a method for detecting D-β-Asp at specific sites in particular proteins, (ii) a likely spontaneous mechanism by which Asp residues in proteins invert and isomerize to the D-β-form with age under physiological conditions, (iii) a discussion of factors that favor such a reaction.
authors: Research Reactor Institute, Kyoto University, Kumatori, Sennan, Osaka 590-0494, Japan. nfujii@rri.kyoto-u.ac.jp
authors: Noriko
authors: N
authors: Fujii
authors: Yuichi
authors: Y
authors: Kaji
authors: Norihiko
authors: N
authors: Fujii
mesh_terms: D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D026603:D-Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D009928:Organ Specificity; D018384:Oxidative Stress; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012867:Skin / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism; D038201:alpha-Crystallins / Q000737:chemistry / Q000378:metabolism
chemical_list: D000596:Amino Acids; D011506:Proteins; D038201:alpha-Crystallins; D026603:D-Aspartic Acid