ISSN:
1573-4927
Keywords:
aldehyde dehydrogenase
;
isozyme
;
human stomach and liver
;
kinetic property
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Substrate and coenzyme specificities of human liver and stomach aldehyde dehydrogenase (ALDH) isozymes were compared by staining with various aldehydes including propionaldehyde, heptaldehyde, decaldehyde, 2-furaldehyde, succinic semialdehyde, and glutamic γ-semialdehyde and with NAD+ or NADP+ on agarose isoelectric focusing gels. ALDH3 isozyme was isolated from a liver via carboxymethyl-Sephadex and blue Sepharose chromatographies and its kinetic constants for various substrates and coenzymes were determined. Consistent with the previously proposed genetic model for human ALDH3 isozymes (Yinet al., Biochem. Genet. 26:343, 1988), a single liver form and multiple stomach forms exhibited similar kinetic properties, which were strikingly distinct from those of ALDH1, ALDH2, and ALDH4 (glutamic γ-semialdehyde dehydrogenase). A set of activity assays using various substrates, coenzymes, and an inhibitor to distinguish ALDH1, ALDH2, ALDH3, and ALDH4 is presented. As previously reported in ALDH1 and ALDH2, a higher catalytic efficiency (V max/K m) for oxidation of long-chain aliphatic aldehydes was found in ALDH3, suggesting that these enzymes have a hydrophobic barrel-shape substrate binding pocket. Since theK m value for acetaldehyde for liver ALDH3, 83 mM, is very much higher than those of ALDH1 and ALDH2, ALDH3 thus represents an unique class of human ALDH isozymes and it appears not to be involved in ethanol metabolism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00554167
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