ALPHA-AMINOISOBUTYRIC-ACID AND ISOVALINE IN TOKYO BAY SEDIMENTS

Two nonprotein amino acids, 2-amino-2-methylpropionic acid (alpha-amin oisobutyric acid, alpha AiBA) and 2-amino-2-methylbutanoic acid (isova line, iVal) were found in modern Tokyo bay sediments together with sev eral protein amino acids. Concentrations of the two nonprotein amino a cids were approximately 1 nmol per g of dry sediment, and the protein amino acids were several hundred to slightly over one thousand nmol pe r g. iVal was found to be nearly racemic, whereas the protein amino ac ids were predominantly in the L-form. We do not consider the two nonpr otein amino acids to be of extraterrestrial origin as suggested by the study of the Cretaceous/Tertiary (K/T) boundary sediments at Stevns K lint (Zhao and Bada, 1989) and propose a terrestrial origin. The sourc e of the two nonprotein amino acids is not biological because the iVal is racemic. They may come from industrial waste water containing C-5 substituted hydantoins which then hydrolyzed to give alpha AiBA and ra cemic iVal. Copyright (C) 1998 Elsevier Science Ltd.