Endoscopy 2004; 36 - 9
DOI: 10.1055/s-2004-834497

Characterization of Cinnamyl Alcohol Dehydrogenase

B Mee 1, H Windle 1, D Kelleher 1, R Malone 1, G Henehan 1
  • 1Dublin Institute of Technology, Cathal Brugha Street, Dublin and Institute of Molecular Medicine, Trinity College, Dublin

Aims: It has been proposed that some of the pathogenesis of H. pylori – mediated damage of the gastric mucosa occurs through the production of toxic aldehydes by H. pylori alcohol dehydrogenases. The alcohol dehydrogenases of H. pylori have not been thoroughly characterized.

Methods: A cinnamyl alcohol dehydrogenase from H. pylori has been cloned and expressed in E. coli and characterised for substrate specificity.

Results: The enzyme was found to be a monomer of 42 kDa. The best alcohol substrate was coniferyl alcohol with a k cat/K m value of 77869min -1·mM. The k cat/K m values cinnamyl alcohol and benzylalcohol were more than an order of magnitude lower. Aliphatic alcohols were poorer substrates with k cat/K m values 10-fold or more lower than the aromatic alcohols. The k cat/K m values for aldehydes were higher than those for alcohols. Of the aldehydes, cinnamylaldehyde was the best substrate followed by benzaldehyde. Acetylaldehyde had a 10-fold lower k cat/K m value than cinnamylaldehyde. The enzyme was found to be capable of the dismutation of benzaldehyde to benzyl alcohol and benzoic acid.

Discussion: Dismutation may provide a means of reducing the concentration of toxic aldehydes within the bacterium.