Lauble_2002_Protein.Sci_11_65

Reference

Title : Structure determinants of substrate specificity of hydroxynitrile lyase from Manihot esculenta - Lauble_2002_Protein.Sci_11_65
Author(s) : Lauble H , Miehlich B , Forster S , Kobler C , Wajant H , Effenberger F
Ref : Protein Science , 11 :65 , 2002
Abstract :

Tryptophan 128 of hydroxynitrile lyase of Manihot esculenta (MeHNL) covers a significant part of a hydrophobic channel that gives access to the active site of the enzyme. This residue was therefore substituted in the mutant MeHNL-W128A by alanine to study its importance for the substrate specificity of the enzyme. Wild-type MeHNL and MeHNL-W128A showed comparable activity on the natural substrate acetone cyanohydrin (53 and 40 U/mg, respectively). However, the specific activities of MeHNL-W128A for the unnatural substrates mandelonitrile and 4-hydroxymandelonitrile are increased 9-fold and approximately 450-fold, respectively, compared with the wild-type MeHNL. The crystal structure of the MeHNL-W128A substrate-free form at 2.1 A resolution indicates that the W128A substitution has significantly enlarged the active-site channel entrance, and thereby explains the observed changes in substrate specificity for bulky substrates. Surprisingly, the MeHNL-W128A--4-hydroxybenzaldehyde complex structure at 2.1 A resolution shows the presence of two hydroxybenzaldehyde molecules in a sandwich type arrangement in the active site with an additional hydrogen bridge to the reacting center.

PubMedSearch : Lauble_2002_Protein.Sci_11_65
PubMedID: 11742123
Gene_locus related to this paper: manes-hnl

Citations formats

Lauble H, Miehlich B, Forster S, Kobler C, Wajant H, Effenberger F (2002)
Structure determinants of substrate specificity of hydroxynitrile lyase from Manihot esculenta
Protein Science 11 :65

Lauble H, Miehlich B, Forster S, Kobler C, Wajant H, Effenberger F (2002)
Protein Science 11 :65