Enzyme - EC 1.1.1.3 Homoserine dehydrogenase
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EC
1.1.1.3
Official Name
Homoserine dehydrogenase
Alternative name(s)
---
Class
1.Oxidoreductases
1.Acting on the CH-OH group of donors
1.With NAD+ or NADP+ as acceptor
Reaction catalysed
L-Homoserine + NAD(P)+ L-Aspartate 4-semialdehyde + NAD(P)H
Substrates
L-Homoserine
NAD+
NADP+
Products
L-Aspartate 4-semialdehyde
NADH
NADPH

Metabolic Pathways
Aspartate, methionine, lysine and threonine synthesis (3D)
Other comments

The yeast enzyme acts most rapidly with NAD+; the Neurospora enzyme with NADP+. The enzyme from E. coli is a multi-functional protein, which also catalyses the reaction of EC 2.7.2.4 (Aspartate kinase).

Homoserine dehydrogenase catalyzes NAD-dependent reduction of aspartate b-semialdehyde into homoserine. This reaction is the third step in a pathway leading from aspartate to homoserine. The latter participates in the biosynthesis of threonine and then isoleucine as well as in that of methionine.

As a signature pattern, it was selected the best conserved region of Hdh. This is a segment of 23 to 24 residues located in the central section and that contains two conserved aspartate residues.
Reference
Expasy Molecular Information Server
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