Influence of Lβ-, Dα- and Dβ-Asp isomers of the Asp-76 residue on the properties of αA-crystallin 70-88 peptide.

Proteins have been considered to consist exclusively of L-amino acids in living tissues. However, our previous studies showed that two specific aspartyl (Asp) residues in αA- and αB-crystallins from human eye lenses invert to the D-isomers to a high degree during aging. The reaction is also accompanied by isomerization into a form containing β-Asp (isoaspartate) residues.