Oh. Kwon et al., HYDROPHOBILIZATION OF ESTERASE BY GENETIC COMBINATION WITH POLYPROLINE OR POLYTYROSINE AT THE CARBOXYL-TERMINAL, Biochimica et biophysica acta. Protein structure and molecular enzymology, 1388(1), 1998, pp. 239-246
Polyproline (Poly-Pro) that is an amphiphilic polypeptide, or polytyro
sine (Poly-Tyr) that is a hydrophobic polypeptide, were connected to t
he carboxy terminus of Pseudomonas sp. esterase by the recombinant DNA
technique. The hydrophobicity of the esterase was enhanced by the int
roduction of Poly-Pro or Poly-Tyr, and also by increasing chain length
of the polypeptides. Poly-Tyr increased the hydrophobicity of esteras
e more than Poly-Pro. Poly-Tyr induced significant conformational chan
ge of fusion esterase, but Poly-Pro did not. Consequently, the introdu
ction of Poly-Tyr led to loss of activity of the fusion enzyme to a ne
gligible level. On the other hand, the Poly-Pro-fusion-esterase retain
ed enzymatic activity and the hydrolytic activity (k(cat)/K-m) of the
fusion esterase carrying 40 proline residues (esterase-Pro40) relative
to that of the wild-type esterase with the substrates p-nitrophenyl-p
ropionate, -pentanoate, and -hexanoate was 1.76, 1.95, and 4.7, respec
tively. The results could be explained in terms of easier access of lo
ng-chain carboxylate to the fusion esterase compared to the wild-type
esterase in aqueous solution. (C) 1998 Elsevier Science B.V. All right
s reserved.