Alanyl ethyl phosphate (1) is an activated derivative of alanine that is functionally related to the corresponding aminoacyl adenylate, the initial activated amino acid intermediate in protein biosynthesis. To establish the inherent reactivity of these species, the kinetic parameters for hydrolysis of alanyl ethyl phosphate in water at 25 degrees C were determined. There is catalysis by acid (k = 4 x 10(-4) M(-1)s(-1)) and base (k = 1.7 M(-1)s(-1)) along with two pH-independent processes (k = 3 x 10(-5) and 1.6 x 10(-3) s(-1)) that are connected as a kinetic titration curve of the amino group of alanyl ethyl phosphate (pK(a) = 7.8). The results are consistent with mechanisms proceeding via addition to the carbonyl of water or hydroxide with proton migrations. Reaction with methanol is slower than reactions with water while reaction with 2-propanol leads to complex products. In solutions sufficiently concentrated for P-31 NMR analysis, alanyl ethyl phosphate also undergoes reactions that produce alanylalanine and other condensation products. Metal ions catalyze the hydrolysis reactions through complex formation. Cupric and zinc ions are most effective (similar to 100-fold larger rate constant than water: association constants > 100 M-1) with magnesium and calcium forming weaker and less reactive complexes. These results show that aminoacyl alkyl phosphates are sufficiently stable to be used in water and that metal ions can facilitate their reactions. Improved catalysts will be needed to facilitate biomimetic processes such as aminoacylation of t-RNA.