New tyrosine metabolites in humans: hawkinsin and cis- and trans-4-hydroxycyclohexylacetic acids. Unusual adsorption of deuterated and non-deuterated hawkinsin during gas chromatography.

In a new inborn error of metabolism, where obviously a defect of 4-hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27) exists, hawkinsin [(2-cystein-S-yl-1,4-dihydroxycyclohex-5-en-1-yl) acetic acid] and cis- and trans-hydroxycyclohexylacetic acids were found in the urine. A partially reversible adsorption of deuterated and non-deuterated hawkinsin (as the penta-trimethylsilyl derivative) in gas chromatography--mass spectrometry has inhibited a mass fragmentographic quantitation of this compound to date. However, quantitation seems to be possible using mass framentography of 1,4-dihydroxycyclohexylacetic acid, formed by desulfuration of the sample with active nickel.