New simple method for purification of class I alcohol dehydrogenase

Ethanol's molecular targets

Ethanol produces a wide variety of behavioral and physiological effects in the body, but exactly how it acts to produce these effects is still poorly understood. Although ethanol was long believed to act nonspecifically through the disordering of lipids in cell membranes, proteins are at the core of most current theories of its mechanisms of action. Although ethanol affects various biochemical processes such as neurotransmitter release, enzyme function, and ion channel kinetics, we are only beginning to understand the specific molecular sites to which ethanol molecules bind to produce these myriad effects. For most effects of ethanol characterized thus far, it is unknown whether the protein whose function is being studied actually binds ethanol, or if alcohol is instead binding to another protein that then indirectly affects the functioning of the protein being studied. In this Review, we describe criteria that should be considered when identifying alcohol binding sites and highlight a number of proteins for which there exists considerable molecular-level evidence for distinct ethanol binding sites.

Interactions of alcohol dehydrogenase to p-hydroxyacetophenone-sepharose and p-acetamidophenol-sepharose

BACKGROUND

p-Hydroxyacetophenone (HAP)-sepharose is known to be an effective ligand for isolation of aldehyde dehydrogenase and chloramphenicol acetyltransferase. In this study, we investigated ligand specificities to alcohol dehydrogenase (ADH) using p-HAP-sepharose and p-acetamidophenol (AAP)-sepharose.

METHODS

p-HAP and p-AAP were coupled to epoxy-activated sepharose and used as ligands for affinity chromatography to detect binding proteins. Fractions of affinity chromatography were collected and separated by SDS-PAGE. Commassie brilliant blue staining was carried out for detecting proteins. For determining protein sequences, polypeptide was separated by HPLC after cleavage of Lys-specific protease digestion.

RESULTS

p-HAP ligands have the ability to bind to seven proteins, including class I ADH extracted from a rat cytosolic fraction as well as HLADH (horse liver ADH). p-HAP, p-AAP and benzaldehyde (10 mM each) could elute HLADH from the complex of HLADH-pHAP-sepharose column. On the other hand, p-AAP-sepharose has no ability to bind to HLADH, although three proteins from a rat liver cytosolic fraction were found to be able to bind to p-AAP-sepharose.

CONCLUSIONS

p-HAP binds to ADH in a structure-specific manner and this binding is nonspecific to species of origin of ADH.

Enhancement of alcohol dehydrogenase activity in vitro by acetylsalicylic acid

The interaction of acetylsalicylic acid with alcohol dehydrogenase was investigated. Horse liver alcohol dehydrogenase bound to a p-hydroxyacetophenone affinity column was eluted by acetylsalicylic acid. In vitro enzymatic activity of alcohol dehydrogenase in the presence of ethanol as a substrate was significantly increased by incubation with acetylsalicylic acid. These results suggest that acetylsalicylic acid has an affinity with alcohol dehydrogenase and enhances its activity.