(3S)-4-(9-Fluorenylmethoxycarbonylamino)-3-methyl(allyloxycarbonyl)aminoethyloxyacetic acid (1) was prepared from (R)-3-aminopropane-1,2-diol and used as branching unit for the synthesis of second generation peptide dendrimers with six individually addressable variable amino acid positions. Three pairs of diastereomeric dendrimers were prepared bearing a common hydrophobic core and permutations of the catalytic triad amino acids aspartate, histidine and serine at the surface. Dendrimers with two surface histidine residues catalyzed the hydrolysis of fluorogenic 8-acyloxypyrene-1,3,6-trisulfonates in aqueous buffer pH 6.0 with rate enhancement k cat /k uncat in the 10 3 range and Michaelis-Menten constants K M in the 10 À 4 M range. Substrate recognition involves electrostatic interactions, as shown by competitive inhibition of catalysis observed with pyrene-1,3,6,8-tetrasulfonate. The 4-fold to 7-fold lowering in K M between the butyryl and nonanoyl esters in the most active dendrimers provides evidence for a hydrophobic component in substrate binding, which is absent in a closely related, less active diastereomeric peptide dendrimer.