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1bxs

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Image:1bxs.jpg

1bxs, resolution 2.35Å

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SHEEP LIVER CLASS 1 ALDEHYDE DEHYDROGENASE WITH NAD BOUND

Overview

Background:. Enzymes of the aldehyde dehydrogenase family are required for, the clearance of potentially toxic aldehydes, and are essential for the, production of key metabolic regulators. The cytosolic, or class 1, aldehyde dehydrogenase (ALDH1) of higher vertebrates has an enhanced, specificity for all-trans retinal, oxidising it to the powerful, differentiation factor all-trans retinoic acid. Thus, ALDH1 is very likely, to have a key role in vertebrate development. Results:. The, three-dimensional structure of sheep ALDH1 has been determined by X-ray, crystallography to 2.35 A resolution. The overall tertiary and quaternary, structures are very similar to those of bovine mitochondrial ALDH (ALDH2), but there are important differences in the entrance tunnel for the, substrate. In the ALDH1 structure, the sidechain of the general base, Glu268 is disordered and the NAD+ cofactor binds in two distinct modes., Conclusions:. The submicromolar Km of ALDH1 for all-trans retinal, and its, 600-fold enhanced affinity for retinal compared to acetaldehyde, are, explained by the size and shape of the substrate entrance tunnel in ALDH1., All-trans retinal fits into the active-site pocket of ALDH1, but not into, the pocket of ALDH2. Two helices and one surface loop that line the tunnel, are likely to have a key role in defining substrate specificity in the, wider ALDH family. The relative sizes of the tunnels also suggest why the, bulky alcohol aversive drug disulfiram reacts more rapidly with ALDH1 than, ALDH2. The disorder of Glu268 and the observation that NAD+ binds in two, distinct modes indicate that flexibility is a key facet of the enzyme, reaction mechanism.

About this Structure

1BXS is a Single protein structure of sequence from Ovis aries with NAD as ligand. Active as Aldehyde dehydrogenase (NAD(+)), with EC number 1.2.1.3 Full crystallographic information is available from OCA.

Reference

Sheep liver cytosolic aldehyde dehydrogenase: the structure reveals the basis for the retinal specificity of class 1 aldehyde dehydrogenases., Moore SA, Baker HM, Blythe TJ, Kitson KE, Kitson TM, Baker EN, Structure. 1998 Dec 15;6(12):1541-51. PMID:9862807

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