title: Alanine synthesis from glyceraldehyde and ammonium ion in aqueous solution.
abstract: Alanine is formed under anaerobic conditions from glyceraldehyde and ammonium ion in aqueous solutions of sodium phosphate (pH 7.0) or imidazole-imidazolium chloride (pH 7.0) at ambient temperature.  In 500 mM imidazole (pH 7.0), alanine synthesis from 10 mM glyceraldehyde and 15 mM ammonium ion is roughly 6 times more rapid in the presence of 10 mM 3-mercaptopropionate (0.62% yield at 60 days) than in its absence (0.10% yield at 60 days).  Likewise, the formation of alanine in 500 mM sodium phosphate (pH 7.0) from 5 mM glyceraldehyde and 10 mM ammonium ion is more rapid in the presence of 10 mM N-acetylcysteine than in its absence.  In this reaction with N-acetylcysteine, the ratio of the yield of alanine to the yield of lactate is fairly constant.  The yield of alanine is about 4.5% that of lactate.  Alanine synthesis in the presence of thiol probably proceeds via alanyl thioester, which is produced by rearrangement of the imine of the hemithioacetal of pyruvaldehyde, a product of glyceraldehyde dehydration.  The significance of this reaction for molecular evolution is discussed.
authors.affiliation: The Salk Institute for Biological Studies, San Diego, California 92138, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Weber
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry; D000409:Alanine / Q000138:chemical synthesis*; D019418:Evolution, Chemical; D019143:Evolution, Molecular; D005561:Formates / Q000737:chemistry; D005985:Glyceraldehyde / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry; D006016:Glycolates / Q000737:chemistry; D019344:Lactic Acid / Q000138:chemical synthesis; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012694:Serine / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D005561:Formates; D006016:Glycolates; D000644:Quaternary Ammonium Compounds; D013438:Sulfhydryl Compounds; C031149:glycolic acid; C030544:formic acid; D019344:Lactic Acid; D005985:Glyceraldehyde; D012694:Serine; D000409:Alanine; D005998:Glycine; D000111:Acetylcysteine