Biogeochemistry of organic matter: polypeptides and amino acids in fossils and sediments in relation to geothermometry

Quantitative data are presented on ninhydrin-reacting substances in hydrolysates and extracts of Recent sediments, sedimentary rocks, and fossils, as determined by column chromatography. The recovery of amino acids added in small amounts to a concentrated calcium chloride solution was found to be 94-96 per cent, after precipitation of the calcium as calcium sulphate and removal of the HCl by vacuum distillation. Seventeen amino acids and three unknowns were detected in hydrolysates of surface and subsurface sediment samples, from Lake Opinicon, Ontario, with amino acids and other ninhydrin-reacting organic compounds accounting for nearly two-thirds of the soluble-N in the hydrolysate, and ammonia for most of the remaining third. Only five amino acids, (aspartic acid, glutamic acid alanine, leucine(s) and γ-aminobutyric acid) and one unidentified ninhydrin-reacting organic compound were present in a hydrolysate of shale from the Green River formation, (Eocene). Amino acids accounted for only 0.014 per cent of the total-N in the shale. It was calculated from the alanine content that the maximum temperature that the Green River shale could have been continuously subjected to during its history was 74°C. Amino acids were not detected in hydrolysates of two pre-Cambrian sedimentary rocks, nor in it hydrolysate of a Miocene lignite. An acid extract of carnosaur "teeth" from the Upper Cretaceous contained leucine(s), ammonia, ethanolamine, and one unidentified ninhydrin-reacting substance that chromatographed similarly to an unknown found in a hydrolysate of laboratory heated Mercenaria shel