First evidence for the occurrence of N delta-acetyl-L-ornithine and quantification of the free amino acids in the cultivated mushroom, Pleurotus ostreatus.

The free amino acid profile of the fruiting bodies of Pleurotus ostreatus was studied in detail. The first evidence for the occurrence of N delta-acetyl-L-ornithine in the mushroom was presented, and 33 ninhydrin-positive compounds were determined, besides N delta-acetyl-L-ornithine. Alanine, glutamic acid, valine, glutamine, glycine and leucine were predominant protein amino acids occurring in the free form. As regards the non-protein amino acids, ornithine, gamma-aminobutyric acid, saccharopine, alpha-aminoadipic acid, ethanolamine, cystathionine, and N-(gamma-glutamyl)ethanolamine were mainly detected. The sum of the nitrogen of the three abundant amino acids, alanine, glutamic acid and ornithine, accounted for about 40% of the total nitrogen in the amino acid fraction.