title: The earliest catabolic pathways.
abstract: Anaerobic catabolism of amino acids may have provided the main source of energy for primitive microorganisms. Examples are given of amino acid catabolic reactions coupled to substrate level phosphorylations occurring in present-day anaerobes which may be biochemical fossils from a very early stage of the evolution of procaryotes.
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000596:Amino Acids / Q000378:metabolism*; D000693:Anaerobiosis; D005075:Biological Evolution; D005285:Fermentation; D005998:Glycine / Q000378:metabolism; D010084:Oxidation-Reduction; D010452:Peptide Biosynthesis; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000255:Adenosine Triphosphate; D011392:Proline; D005998:Glycine