Sandbox Reserved 328
This Sandbox is Reserved from January 10, 2010, through April 10, 2011 for use in BCMB 307-Proteins course taught by Andrea Gorrell at the University of Northern British Columbia, Prince George, BC, Canada. |
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1kar, resolution 2.10Å () | |||||||||
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Ligands: | , | ||||||||
Non-Standard Residues: | |||||||||
Gene: | HISD (Escherichia coli) | ||||||||
Activity: | Histidinol dehydrogenase, with EC number 1.1.1.23 | ||||||||
Related: | 1k75, 1kae, 1kah | ||||||||
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Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
Coordinates: | save as pdb, mmCIF, xml |
L-Histidinol DehydrogenaseL-Histidinol Dehydrogenase
The enzyme l-histidinol dehydrogenase (HisD) Basic information, current knowledge of areas found, etc. Structural
Overall StructureOverall Structure
HisD is a homodimer, with each subunit consisting of a globule segment, and an extending tail. The two larger domains (1 and 2) are within the globule, and domains 3 and 4 are found in the tail. The cores of both domains (residues 124–236 in domain 1 & 237–381 in domain 2) adopt incomplete Rossmann folds, which lack the last strand-helix hairpin[1]. To carry out its function, HisD relies on the presence of one Zn2+ cation per monomer, not for catalysis, but for substrate binding. The Zn2+ cation is located at the bottom of the cavity occupied by the substrate and is octahedrally coordinated by four seperate residues. Along with Zn, the coordination of the substrate in the active site is assisted by the large degree of secondary structure present in the protein. The substrate binds in a deep pocket formed at the dimer interface between domains 1, 2, and 4, with most interactions being with residues at the N-terminal end of the β-sheet found within domain 2. Large amounts of secondary structure both in the form of and are present, and serve to provide a base for the overall structure of the molecule.
Enzymatic mechanismEnzymatic mechanism
Other informationOther information
ReferencesReferences
- ↑ 1.0 1.1 1.2 Barbosa JA, Sivaraman J, Li Y, Larocque R, Matte A, Schrag JD, Cygler M. Mechanism of action and NAD+-binding mode revealed by the crystal structure of L-histidinol dehydrogenase. Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):1859-64. Epub 2002 Feb 12. PMID:11842181 doi:10.1073/pnas.022476199