title: Prebiotic syntheses of vitamin coenzymes:  II.  Pantoic acid, pantothenic acid, and the composition of coenzyme A.
abstract: Pantoic acid can by synthesized in good prebiotic yield from isobutyraldehyde or alpha-ketoisovaleric acid + H2CO + HCN.  Isobutyraldehyde is the Strecker precursor to valine and alpha-ketoisovaleric acid is the valine transamination product.  Mg2+ and Ca2+ as well as several transition metals are catalysts for the alpha-ketoisovaleric acid reaction.  Pantothenic acid is produced from pantoyl lactone (easily formed from pantoic acid) and the relatively high concentrations of beta-alanine that would be formed on drying prebiotic amino acid mixtures.  There is no selectivity for this reaction over glycine, alanine, or gamma-amino butyric acid.  The components of coenzyme A are discussed in terms of ease of prebiotic formation and stability and are shown to be plausible choices, but many other compounds are possible.  The gamma-OH of pantoic acid needs to be capped to prevent decomposition of pantothenic acid.  These results suggest that coenzyme A function was important in the earliest metabolic pathways and that the coenzyme A precursor contained most of the components of the present coenzyme.
authors.affiliation: Department of Chemistry, University of California, San Diego, La Jolla 92093-0317.
authors.forename: S L
authors.initials: SL
authors.lastname: Miller
authors.forename: G
authors.initials: G
authors.lastname: Schlesinger
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000502:physiology; D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism; D003065:Coenzyme A / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D003067:Coenzymes / Q000096:biosynthesis*; D005998:Glycine / Q000737:chemistry / Q000378:metabolism; D045782:Hemiterpenes; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000138:chemical synthesis*; D007651:Keto Acids / Q000737:chemistry / Q000378:metabolism; D010205:Pantothenic Acid / Q000096:biosynthesis*; D011498:Protein Precursors / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D000447:Aldehydes; D003067:Coenzymes; D045782:Hemiterpenes; D006885:Hydroxybutyrates; D007651:Keto Acids; D011498:Protein Precursors; C016031:pantoic acid; D010205:Pantothenic Acid; C001505:alpha-ketoisovalerate; C005412:pantolactone; D000255:Adenosine Triphosphate; C017439:isobutyraldehyde; D000409:Alanine; D015107:4-Butyrolactone; D003065:Coenzyme A; D005998:Glycine