Engineering Klebsiella sp. 601 multicopper oxidase enhances the catalytic efficiency towards phenolic substrates.

ABSTRACT:

Background

Structural comparison between bacterial CueO and fungal laccases has suggested that a charged residue Glu (E106) in CueO replaces the corresponding residue Phe in fungal laccases at the gate of the tunnel connecting type II copper to the protein surface and an extra α-helix (L351-G378) near the type I copper site covers the substrate binding pocket and might compromise the electron transfer from substrate to type I copper. To test this hypothesis, several mutants were made in Klebsiella sp. 601 multicopper oxidase, which is highly homologous to E. coli CueO with a similarity of 90% and an identity of 78%.

Results

The E106F mutant gave smaller K(m) (2.4-7 fold) and k(cat) (1-4.4 fold) values for all three substrates DMP, ABTS and SGZ as compared with those for the

SUBMITTER: Li Y 

PROVIDER: S-EPMC3123277 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature