Prolidase deficiency diagnosed by 1H NMR spectroscopy of urine

Three urine samples from two prolidase‐deficient patients were analysed using 1H NMR spectroscopy. One‐dimensional 1H NMR spectra showed a characteristic pattern of overlapping resonances of the proline and hydroxyproline protons of the imidodipeptides. The model compounds Ala‐Pro, Gly‐Pro, Phe‐Pro, Leu‐Pro, Val‐Pro, Gly‐Hyp and Pro‐Hyp were measured as well. The non‐proline resonances of Val‐Pro, Ala‐Pro and Gly‐Pro could be assigned in the urine spectra. These resonances could then be used for quantification of the corresponding imidodipeptids. The presence of Leu‐Pro in the patients' urine was demonstrated by the results of COSY experiments. However, this imidodipeptide could not be quantified owing to overlap of the resonaces in the one‐dimensional 1H NMR spectrum of the patients' urine. Phe‐Pro, Pro‐Hyp and Gly‐Hyp could not be assigned in the spectrum of the patient's urine. The characteristic resonances in the urine from a prolidase‐deficient patient, i.e. Ala‐Pro, Val‐Pro, Gly‐Pro, and resonances of the (hydroxy)proline part of the imidodipeptides can be used to diagnose this disease.