Synthesis and Enzymatic Carboxylation of a Biotin-containing Peptide Representing the Coenzyme Binding Site of E. coli Acetyl–CoA Carboxylase

A biotin-containing pentapeptide Boc–Glu–Ala–Met–Bct–Met (1) that corresponds to the coenzyme binding site of E. coli acetyl–CoA carboxylase has been prepared. Peptide 1 as well as free biotin served as a substrate for the carboxylation reaction catalyzed by the biotin carboxylase subunit dimer of E. coli acetyl–CoA carboxylase. The Michaelis constant, Km, and the maximum velocity, Vmax, for 1 were 18 mM and 2.8 μM min−1 (1 M=1 mol dm−3), respectively. The corresponding values for biotin were 214 mM and 28 μM min−1. Thus, the overall reactivity (Vmax⁄Km) of peptide 1 exceeded that of biotin by 20%.