Hydrolytic properties of phenylalanyl- and N-acetylphenylalanyl adenylate anhydrides.
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.
Lacey
J C
JC
Department of Biochemistry, University of Alabama in Birmingham, USA.
Senaratne
N
N
Mullins
D W
DW
D000249:Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D002384:Catalysis; D019143:Evolution, Molecular; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D010452:Peptide Biosynthesis; D011506:Proteins / Q000138:chemical synthesis
D002254:Carbonates; D011506:Proteins; C042022:phenylalanyl-AMP anhydride; D000249:Adenosine Monophosphate; C048994:N-acetylphenylalanyl-adenosine monophosphate-anhydride