Hydrolytic properties of phenylalanyl- and N-acetylphenylalanyl adenylate anhydrides

• Published in: Origins of life and evolution of biospheres Vol. 15; no. 1; p. 45
• Main Authors: Lacey, Jr, J C, Senaratne, N, Mullins, Jr, D W
• Format: Journal Article
• Language: English
• Published: Netherlands 01.03.1984
• Subjects: Adenosine Monophosphate - analogs & derivatives; Adenosine Monophosphate - chemistry; Carbonates - chemistry; Catalysis; Evolution, Molecular; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Peptide Biosynthesis; Proteins - chemical synthesis
• ISSN: 0169-6149
• DOI: 10.1007/BF01809392

We have used a novel spectrophotometric method to study the hydrolysis of N-acetylphenylalanyl adenylate anhydride (AcPhe-AMP) and phenylalanyl-adenylate anhydride (Phe-AMP) at low concentrations (10(-5) M), 25 degrees C, constant buffer concentration (0.05 M), and as a function of pH. While Phe-AMP is susceptible principally to attack by OH-, with two different rates depending on whether the alpha-amino group of the amino acid is protonated or not, the AcPhe-AMP is susceptible to acid decomposition as well. At pH's 4-8, the Phe-AMP hydrolyzes faster than the AcPhe-AMP, but at pH less than 4 or pH greater than 8, the blocked form hydrolyzes faster. Both forms are also attacked by H2O, and at the same rate. Moreover, the hydrolysis of Phe-AMP is shown to be greatly catalyzed by carbonate, although the AcPhe-AMP is not subject to such catalysis. The rate laws for the various mechanisms and the activation energies for the hydrolyses at pH 7.1 are given.