The expression in E. coli of a polymeric gene coding for an esterase mimic catalyzing the hydrolysis of p-nitrophenyl esters.

We have prepared a hybrid protein consisting of seven esterase units, Glu-Ala-His-Ala-Ser-Phe-Phe-Phe, fused to the N-terminal of galactokinase (E. coli). The structural gene for this bifunctional protein was obtained by cloning a polymer made up of three chemically synthesized oligonucleotides to which the galactokinase gene was fused in frame. The hybrid protein was purified to homogeneity with the aid of the galactokinase moiety and showed an Mr of 51,000-53,000. The preparation could catalyze the hydrolysis of p-nitrophenyl esters and, due to the inbuilt hydrophobic spacers, Phe-Phe-Phe, improved catalysis of more hydrophobic substrates was obtained.