Aldehyde dehydrogenase in blood: a sensitive assay and inhibition by disulfiram.
The characteristics of human blood aldehyde dehydrogenase with indole-3-acetaldehyde as the substrate were investigated. Blood volumes of less than 25 microliter could be assayed. The Km-value was below 10 microM for indole-3-acetaldehyde and 100 microM for NAD+. The ALDH-activity appeared to be located exclusively in the intracellular fraction of the erythrocytes. Acetaldehyde or ethanol at concentrations up to 1 and 40 mM respectively did not affect the activity. Disulfiram caused a pronounced inhibition of the enzyme both in vitro and in vivo. The blood ALDH-activity in disulfiram-treated patients was not fully restored until 6 weeks after discontinuation of the treatment. The inhibition observed in vitro was reversed completely by 2-mercaptoethanol but only partially by glutathione. No restoration of activity in blood from disulfiram-treated patients was obtained with these two reagents. The inhibition found in vitro and in vivo was more pronounced when the assays were performed with indole-3-acetaldehyde than with acetaldehyde. The results suggest that different isozymes of ALDH are involved in the assay with these two substrates.
D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000201:enzymology; D000444:Aldehyde Dehydrogenase; D000445:Aldehyde Oxidoreductases / Q000037:antagonists & inhibitors / Q000097:blood*; D000818:Animals; D004221:Disulfiram / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007211:Indoles; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D051379:Mice; D008875:Middle Aged
D007211:Indoles; C001655:indole-3-acetaldehyde; D000445:Aldehyde Oxidoreductases; D000444:Aldehyde Dehydrogenase; D004221:Disulfiram