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Table 1 Human ADH and ALDH family members involved in the metabolism of ethanol

From: Effect of the allelic variants of aldehyde dehydrogenase ALDH2*2 and alcohol dehydrogenase ADH1B*2on blood acetaldehyde concentrations

Enzyme Class Gene
locus
Allelic
Variant
Subunit
composition
K m
(mM)
V max
(U/mg)
Vmax/Km
(U/mg/mM)
ADH I ADH1A   αα 5.2 0.24 0.047
   ADH1B ADH1B*1 β1β1 0.016 0.18 12
    ADH1B*2 β2β2 1.9 4.8 2.6
    ADH1B*3 β3β3 53 3.2 0.060
   ADH1C ADH1C*1 γ1γ1 0.11 0.81  
    ADH1C*2 γ2γ2 0.061 0.47  
  II ADH2   ππ 23 0.30 0.013
  III ADH3   χχ 3,400 0.83  
  IV ADH4   μμ(σσ) 58 11 0.19
ALDH I ALDH1A1   Tetramer 0.033 0.63 19
  II ALDH2 ALDH2*1 Tetramer(E4) 0.00020 0.60 3,000
    ALDH2*2 Tetramer(K4) 0.0046 0.017 3.6
  1. Enzyme activity was determined in 0.1M sodium phosphate, at pH 7.5 and 25°C. Samples contained 0.5 mM nicotinamide adenine dinucleotide (NAD; ie a cytosolic oxidised coenzyme concentration in hepatocytes), and various concentrations of ethanol for alcohol dehydrogenase (ADH) or of acetaldehyde for aldehyde dehydrogenase (ALDH). γ1γ12γ2 and χχ exhibit negative and positive cooperativity, respectively; hence they do not have a Km and the values shown are S0.5. Enzyme activity units (U) are expressed as micromoles NADH formed per minute under the assay conditions. Data are from Yin and Agarwal,[1] Yin et al [9]. and Lee et al [10].