Simultaneous racemization and isomerization at specific aspartic acid residues in αB-crystallin from the aged human lens
| Autor: | Masahiko Fujino, Kenshi Satoh, Yoshihiro Ishibashi, Kaoru Harada, Norko Fujii |
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| Rok vydání: | 1994 |
| Předmět: |
Aging
Stereochemistry Sequence analysis Molecular Sequence Data Biophysics Mass spectrometry Biochemistry chemistry.chemical_compound Methionine Isomerism Succinimide Structural Biology Crystallin Aspartic acid Humans Trypsin Amino Acid Sequence Amino Acids Molecular Biology Racemization Aged Aged 80 and over Aspartic Acid Infant Stereoisomerism Sulfoxide Crystallins eye diseases chemistry sense organs Peptides Oxidation-Reduction Isomerization |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology. 1204:157-163 |
| ISSN: | 0167-4838 |
| DOI: | 10.1016/0167-4838(94)90003-5 |
| Popis: | We provide evidence that the racemization and isomerization of aspartyl(Asp) residues occur simultaneously in the alpha B-crystallin in the lens of aged (mean age: 80 years) and young (age: 11 months) humans. We purified alpha B-crystallin and subjected it to tryptic digestion. The resulting peptides were separated by reverse-phase high-performance chromatography (RP-HPLC) and were characterized by amino-acid composition, sequence analysis and mass spectrometry. Two specific sites, Asp-36 (D/L of Asp: 0.92) and Asp-62(D/L of Asp: 0.57), among 13 Asp/asparginyl (Asn) residues in aged alpha B-crystallin, were found to be highly racemized and isomerized to form beta-Asp residues. The beta-Asp-containing peptides were clearly distinguished from normal Asp-containing (alpha-Asp) peptides by RP-HPLC. The racemization and isomerization of Asp residues in aged alpha B-crystallin may occur via a succinimide intermediate. In young alpha B-crystallin, we observed neither racemization nor isomerization. We also found that Met-68 was oxidized to form Met sulfoxide to a greater extent in aged alpha B-crystallin than in young alpha B-crystallin. We concluded that racemization, isomerization, and oxidation of alpha B-crystallin occur spontaneously in the aging process. |
| Databáze: | OpenAIRE |
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