N-Substituted amino acids in serum of patients with chronic renal insufficiency

Abstract

Three N-substituted amino acids were determined in sera from healthy subjects: glycine, glutamic acid and α-alanine (traces only of the last). In the serum of uremic patients the levels of these amino acids were significantly increased; moreover, aspartic acid, cystine, phenylalanine and proline (all in trace quantities) were detected. Next, amino acids found in the N-substituted form were determined quantitatively in blood peptides. The levels of all examined peptide-bound amino acids, except aspartic acid, were significantly changed in uremia: α-alanine, cystine, phenylalanine and glutamic acid levels were significantly decreased, while the ratio of the N-substituted to peptide-bound amino acids was elevated, and the levels of peptide bound glycine were significantly increased.