Some analogies between prebiotic thermal conversions of glycine and metabolic pathways.

The reaction schemes suggested earlier for thermal transformation of glycine into amino acids and carboxylic acids are considered in detail. Close analogy with some wide-spread biochemical reactions of amino acids is observed. The pathway suggested has some common stages with the tricarboxylic acid cycle and other metabolic processes. The possible role of alpha-imino or alpha-keto acids as prebiological analogs of pyridoxal-phosphate-containing enzymes is discussed. The thermal transformations of glycine under primitive Earth conditions could be considered as evolutionary precursors of some present-day metabolic pathways.

Formation of amino acids on heating glycine with alumina.

The conversion of glycine into amino acids on heating at 240 degrees C with basic manganous carbonate and alumina is investigated. Alanine, alpha-aminobutyric acid, norvaline, norleucine, sarcosine, N-ethylglycine, N-methylalanine, N-ethylalanine, aspartic acid and glutamic acid are identified among the products of the reaction. Paper chromatography, ion-exchange chromatography and nuclear magnetic resonance are used for the analysis. A scheme for the observed transformations is presented and it is suggested that it may have been a pathway for the synthesis of amino acids from glycine under primitive Earth conditions.