Liquid chromatography-mass spectrometry for the qualitative analyses of iminodipeptides in the urine of patients with prolidase deficiency.

Analyses of standard iminodipeptides and iminodipeptides in the urine of patients with prolidase deficiency have been demonstrated using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system. The separation was carried out on a reversed-phase column using 0.1% aqueous trifluoroacetic acid-methanol (70:30 or 80:20). Very intense quasi-molecular ions [( M + H]+) of various standard iminodipeptides were observed by this method. The quasi-molecular ions [M + H]+ of various iminodipeptides were also observed in the urine samples of patients with prolidase deficiency, and Gly-Pro, Ala-Pro, Val-Pro, Leu-Pro, Ile-Pro, Ser-Pro, Thr-Pro, Glu-Pro, Asp-Pro, His-Pro, Lys-Pro, Pro-Pro and Tyr-Pro as iminodipeptides containing proline with C-terminal residue and Glu-Hyp, Pro-Hyp, Ile-Hyp and Gly-Hyp as iminodipeptides containing hydroxyproline with C-terminal residue were identified in the urine of patients with prolidase deficiency.