A trial to determine D-amino acids in tissue proteins of mice

Eleven neutral amino acids and two acidic amino acids in tissue proteins of mouse kidney, liver and brain were analyzed for the presence of D-enantiomers. The proteins were hydrolyzed with HCl for 6 h. Of the thirteen amino acids investigated, the presence of D-enantiomers of serine, alanine, proline, aspartate and glutamate (including asparagine and glutamine) was shown in the hydrolysates. However, the level of D-enantiomers were not significantly higher than that of 6-h hydrolysate of serum albumin examined as a control protein. Serum albumin was shown to contain no D-amino acid residues.