Abstract |
d-Serine dehydratase from Saccharomyces cerevisiae (DsdSC) is a fold-type III pyridoxal 5'-phosphate-dependent enzyme catalyzing d- serine dehydration. The enzyme contains 1 mol Zn(2+) in its active site and shows a unique zinc dependence. The Zn(2+) is essential for the d- serine dehydration, but not for the α,β-elimination of β-Cl-d- alanine catalyzed as a side-reaction. The fact that dehydration of d- threonine and d-allo- threonine, also catalyzed by DsdSC, is likewise Zn(2+) dependent indicates that Zn(2+) is indispensable for the elimination of hydroxyl group, regardless of the stereochemistry of C(β) . Removal of Zn(2+) results in a less polar active site without changing the gross conformation of DsdSC. (1) H NMR determined the rates of α- hydrogen abstraction and hydroxyl group elimination of d- serine in (2) H(2) O to be 9.7 and 8.5 s(-1) , respectively, while the removal of Zn(2+) abolished both reactions. Mutation of Cys400 or His398 within the Zn(2+) binding sites to Ala endowed DsdSC with similar properties to those of the Zn(2+) -depleted wild-type enzyme: the mutants lost the reactivity toward d- serine and d- threonine but retained that toward β-Cl-d- alanine. (1) H NMR analysis also revealed that both α- hydrogen abstraction and hydroxyl group elimination from d- serine were severely hampered in the C400A mutant. Our data suggest that DsdSC catalyzes the α- hydrogen abstraction and hydroxyl group elimination in a concerted fashion.
|
Authors | Tomokazu Ito, Kazushi Koga, Hisashi Hemmi, Tohru Yoshimura |
Journal | The FEBS journal
(FEBS J)
Vol. 279
Issue 4
Pg. 612-24
(Feb 2012)
ISSN: 1742-4658 [Electronic] England |
PMID | 22176976
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
Copyright | © 2011 The Authors Journal compilation © 2011 FEBS. |
Chemical References |
- Hydroxides
- Saccharomyces cerevisiae Proteins
- Water
- Serine
- Hydrogen
- hydroxide ion
- Hydro-Lyases
- D-serine dehydratase
- Zinc
|
Topics |
- Amino Acid Substitution
- Binding Sites
(genetics)
- Biocatalysis
(drug effects)
- Catalytic Domain
(genetics)
- Hydro-Lyases
(chemistry, genetics, metabolism)
- Hydrogen
(chemistry, metabolism)
- Hydroxides
(chemistry, metabolism)
- Kinetics
- Magnetic Resonance Spectroscopy
- Models, Molecular
- Mutation
- Protein Structure, Tertiary
- Saccharomyces cerevisiae
(enzymology, genetics)
- Saccharomyces cerevisiae Proteins
(chemistry, genetics, metabolism)
- Serine
(chemistry, genetics, metabolism)
- Spectrometry, Fluorescence
- Water
(chemistry, metabolism)
- Zinc
(chemistry, metabolism, pharmacology)
|