Omega-oxidation of 20-hydroxyeicosatetraenoic acid (20-HETE) in cerebral microvascular smooth muscle and endothelium by alcohol dehydrogenase 4.

20-Carboxyeicosatetraenoic acid (20-COOH-AA) is a bioactive metabolite of 20-hydroxyeicosatetraenoic acid (20-HETE), an eicosanoid that produces vasoconstriction in the cerebral circulation. We found that smooth muscle (MSMC) and endothelial (MEC) cultures obtained from mouse brain microvessels convert [3H]20-HETE to 20-COOH-AA, indicating that the cerebral vasculature can produce this metabolite. The [3H]20-COOH-AA accumulated primarily in the culture medium, together with additional radiolabeled metabolites identified as the chain-shortened dicarboxylic acids 18-COOH-18:4, 18-COOH-18:3, and 16-COOH-16:3.

Enzymatic mechanism of low-activity mouse alcohol dehydrogenase 2.

ADH2 is a member of one of the six classes of mammalian alcohol dehydrogenases, which catalyze the reversible oxidation of alcohols using NAD(+) as a cofactor. Within the ADH2 class, the rodent enzymes form a subgroup that exhibits low catalytic activity with all substrates that were examined, as compared to other groups, such as human ADH2. The low activity can be ascribed to the rigid nature of the proline residue at position 47 as the activity can be increased by approximately 100-fold by substituting Pro47 with either His (as found in human ADH2), Ala, or Gln.

Specificity of human alcohol dehydrogenase 1C*2 (gamma2gamma2) for steroids and simulation of the uncompetitive inhibition of ethanol metabolism.

The steady-state kinetics of the recombinant human alcohol dehydrogenase (ADH) 1C*2 with steroids were studied in order to determine substrate and inhibitor specificity. The assays were carried out under conditions of pH and temperature that are similar to those found in vivo. The enzyme has measurable activity on 5beta-androstan-17beta-ol-3-one, 5beta-androstan-3beta-ol-17-one, 5beta-pregnan-3beta-ol-20-one and 5beta-pregnan-3,20-dione, but much less activity with 5beta-cholanic acid-3-one or 5alpha-pregnan-3beta-ol-20-one.