Unknown

Dataset Information

0

Structure determinants of substrate specificity of hydroxynitrile lyase from Manihot esculenta.


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.

SUBMITTER: Lauble H 

PROVIDER: S-EPMC2368774 | biostudies-literature | 2002 Jan

REPOSITORIES: biostudies-literature

altmetric image

Publications

Structure determinants of substrate specificity of hydroxynitrile lyase from Manihot esculenta.

Lauble Hanspeter H   Miehlich Burkhard B   Förster Siegfried S   Kobler Christoph C   Wajant Harald H   Effenberger Franz F  

Protein science : a publication of the Protein Society 20020101 1


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  ...[more]

Similar Datasets

| S-EPMC2374195 | biostudies-literature
| S-EPMC4242363 | biostudies-literature
| S-EPMC2144128 | biostudies-other
2024-05-28 | GSE225366 | GEO
| S-EPMC4723133 | biostudies-literature
| S-EPMC4328001 | biostudies-literature
2024-05-28 | GSE225361 | GEO
| S-EPMC7241714 | biostudies-literature
2016-10-02 | E-MTAB-5110 | biostudies-arrayexpress
| S-EPMC21904 | biostudies-literature