Identification ofN‐acetyl‐S‐(3‐oxo‐3‐carboxy‐n‐propyl)cysteine in the urine of a patient with cystathioninuria using LC/APCI‐MS

Abstract

A new cystathionine metabolite has been identified in the urine of a patient with cystathioninuria using liquid chromatography-mass spectrometry with an atmospheric pressure chemical ionization interface system (LC/APCI-MS). By this method a very intense quasi-molecular ion was observed as a base peak of synthetic N-acetyl-S-(3-oxo-3-carboxy-n-propyl)cysteine (NAc-OCPC). The quasimolecular ion [M + H]+ of NAc-OCPC observed in the urine of a patient with cystathioninuria was the same as that of the authentic compound (m/z 264). The retention time and Rf value on paper chromatography of the synthetic compound were the same as those of the urinary compound from the patient with cystathioninuria. From these results, this new cystathionine metabolite was identified as N-acetyl-S-(3-oxo-3-carboxy-n-propyl)cysteine.

Cystathionine Protects against Endoplasmic Reticulum Stress-induced Lipid Accumulation, Tissue Injury, and Apoptotic Cell Death

“…The level of these compounds increase in direct proportion to the scale of the accumulation of cystathionine (32). The increase in the levels of these cystathionine metabolites is not an artifact of the PPG compound itself as all of these metabolites been identified previously at elevated levels in the urine of patients with cystathioninuria due to mutational inactivation of the human CGL gene (33). This is a generic concern in interpreting protective effects of a compound where the biochemistry, regulation, and tissue distribution of its metabolism are incompletely understood.…”