. Aspects of the origin of life. Life; Biochemistry; Biochemistry; Biogenesis. A Chemical Theory of Spontaneous Generation 149 volatilize byproduct water, Huffman had shown in 1942 [8] that the production of dipeptides from amino acids at 298°K by any route, requires an input of 2000-4000 cal. per mole of dipeptide formed (Table i). Table i Free-energy change accompanying formation of dipeptides from amino acids Alanine + Glycine = Alanylglycine + water A F°298 = 3730 cal. Glycine + Glycine = Glycylglycine + water A F°298 = 3230 cal. Leucine + Glycine = Leucylglycine + water A F°298 = 2960 cal
. Aspects of the origin of life. Life; Biochemistry; Biochemistry; Biogenesis. A Chemical Theory of Spontaneous Generation 149 volatilize byproduct water, Huffman had shown in 1942 [8] that the production of dipeptides from amino acids at 298°K by any route, requires an input of 2000-4000 cal. per mole of dipeptide formed (Table i). Table i Free-energy change accompanying formation of dipeptides from amino acids Alanine + Glycine = Alanylglycine + water A F°298 = 3730 cal. Glycine + Glycine = Glycylglycine + water A F°298 = 3230 cal. Leucine + Glycine = Leucylglycine + water A F°298 = 2960 cal. Benzoic acid + Glycine = Hippuric acid + water A F°298 = 2260 cal. (From H. M. Huffman, J. phys. Chem., 46, 890, 1942) One can calculate that the AF value is more favourable at higher temperatures for the dry reaction in the forward direction, but a destructively high tempera- ture is nevertheless indicated for an energetically spontaneous reaction. One can visualize, however, an overcoming of the energetic barrier by the occurrence of a temperature sufficient to remove water in the gaseous state: H2NCHRCOOH + H2NCHR-COOH = H2NCHRCONHCHR'COOH + H2O f When experiments of this sort were first performed, unexpected indications of the production of more amino acids than those taken for the reactions were found. From this begirming, experimental results often paralleled by thermal experiments described in the early literature, led to a picture of thermal pathways. Some of these results are depicted in Figs, i and 234567 89 10 11 Fig. I. Tracing of chromatogram of products from ammonium salts of Krebs-cycle acids. (i) 10 fil. of aspartic acid standard; (2) 10 //I. of alanine standard; (3) 10 /nl. of leucine standard, to permit comparisons of i^^; (4) 10/d. of unhealed mono- ammonium fumarate; (5) 10 jul. of unheated monoammonium malate; (6) 10 /d. of heated monoammonium fumarate: (7) 2 /d. of hydrolysed heated monoammonium fumarate (2 /til.); (8) 10 /nl. of heated monoammo
Size: 1818px × 1375px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookco, booksubjectbiochemistry, booksubjectlife
