Liver alcohol dehydrogenase in Japanese: high population frequency of atypical form and its possible role in alcohol sensitivity.

Electrophoretic and quantitative studies reveal that 85% of Japanese carry an atypical liver alcohol dehydrogenase (ADH). The frequency of ADH polymorphism is identical with the reported frequency of alcohol sensitivity in the Japanese population. This identity in population frequencies points to a causative relationship between the two phenomena and suggests that alcohol sensitivity might be due to the increased acetaldehyde formation in individuals carrying the atypical ADH gene.     

Population genetic studies on aldehyde dehydrogenase isozyme deficiency and alcohol sensitivity

Population genetic studies on aldehyde dehydrogenase polymorphism using hair-root samples were performed on Europeans, Liberians, Sudanese, Egyptians, Kenyans, Vietnamese, Japanese, Indonesians, Chinese, Thais, and South American Indians. A possible correlation between ALDH I deficiency and sensitivity to alcohol in Oriental populations is discussed.     

Genotypes of alcohol dehydrogenase and aldehyde dehydrogenase loci in Japanese alcohol flushers and nonflushers

Summary A much higher incidence of alcohol flushing among Orientals in comparison to Caucasians, i.e., >50% vs 5%–10%, has been attributed to racial differences in alcohol-metabolizing enzymes. A large majority of Orientals are atypical in alcohol dehydrogenase-2 locus (ADH ₂ ), and their livers exhibit significantly higher ADH activity than the livers of most Caucasians. Approximately 50% of Orientals lack the mitochondrial aldehyde dehydrogenase (ALDH₂) activity, and elimination of acetaldehyde might be disturbed. We determined by means of hybridization of genomic DNA samples with allele specific oligonucleotide probes, genotypes of the ADH ₂ and ALDH ₂ loci in Japanese alcohol flushers and nonflushers. We found that all individuals with homozygous atypical ALDH ₂ ² /ALDH ₂ ² and most of those with heterozygous atypical ALDH ₁ ² /ALDH ₂ ² were alcohol flushers, while all subjects with homozygous usual ALDH ₁ ² /ALDH ₁ ² were nonflushers. Frequency of the atypical ADH ₂ ² was found to be higher in alcohol flushers than in nonflushers, but the statistical significance was not established in the sample size examined.     

Human liver aldehyde dehydrogenase in Chinese and Asiatic Indians: Gene deletion and its possible implications in alcohol metabolism

Two separate human liver aldehyde dehydrogenases exist which show differences in substrate specificity, cation inhibition or activation, and molecular weight. In this paper we report a common absence of enzyme 2 in Chinese which may be taken to indicate a gene deletion coding for this enzyme. The possible implication of this gene deletion among Chinese is discussed.     

Effect of alcohol intoxication and aldehyde dehydrogenase inhibitors on lipid peroxidation in rat liver

A single intraperitoneal administration of ethanol (3.5 g/kg) to rats induced a marked increase in lipid peroxidation and a decrease of antioxidative activity in the liver after 1 h when assessed by chemi-luminescence in liver homogenates. The pretreatment with aldehyde dehydrogenase inhibitor, disulfiram (200 mg/kg 24 hr before ethanol), caused a 10-fold elevation of the blood acetaldehyde levels, with no effect on the hepatic lipid peroxidation compared to control. Cyanamide (50 mg/kg, 2 h before the ethanol) increased approximately 100-fold the acetaldehyde levels, however, the changes in lipid peroxidation were not significantly different from that produced by ethanol alone. The present results suggest, that the metabolism of acetaldehyde and not acetaldehyde itself is responsible for the in vivo activation of lipid peroxidation during acute alcohol intoxication. Disulfiram prevents the ethanol-induced lipid peroxidation in the rat liver.     

Liver alcohol and aldehyde dehydrogenase isozymes in a Chinese population in Hong Kong

The distribution of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isozymes in the livers of a Chinese population in Hong Kong was examined. Among the 90 livers examined, 7 were typical ADH phenotype consisting the normal beta 1-type isozymes and 83 were atypical phenotype consisting the beta 2-type isozymes. Livers of 48 subjects were of deficient type in ALDH containing ALDH-II alone and 42 were of normal type with both ALDH-I and ALDH-II. When the combination of ADH and ALDH isozymes is considered, the Chinese population in Hong Kong falls into 4 subgroups. For each group, the rates of ethanol and acetaldehyde clearance have a distinct and characteristic potential which is directly related to its particular combination of isozymes.     

The involvement of alcohol dehydrogenase and aldehyde dehydrogenase in alcohol/aldehyde metabolism in Drosophila melanogaster

In this study we have examined the roles of alcohol dehydrogenase, aldehyde oxidase, and aldehyde dehydrogenase in the adaptation of Drosophila melanogaster to alcohol environments. Fifteen strains were characterized for genetic variation at the above loci by protein electrophoresis. Levels of in vitro enzyme activity were also determined. The strains examined showed considerable variation in enzyme activity for all three gene-enzyme systems. Each enzyme was also characterized for coenzyme requirements, effect of inhibitors, subcellular location, and tissue specific expression. A subset of the strains was chosen to assess the physiological role of each gene-enzyme system in alcohol and aldehyde metabolism. These strains were characterized for both the ability to utilize alcohols and aldehydes as carbon sources as well as the capacity to detoxify such substrates. The results of the above analyses demonstrate the importance of both alcohol dehydrogenase and aldehyde dehydrogenase in the in vivo metabolism of alcohols and aldehydes.     

The harmful action of ethanol on the liver: the role of alcohol dehydrogenase and aldehyde dehydrogenase

White rats were divided into water-preferring (WP) and ethanol-preferring (EP) groups, on the basis of their preferable drink: either water or 15% solution of ethanol. Each of these groups was then subdivided into groups which were given to drink for 1 year 15% solution of ethanol (ethanol-treated) or water (controls). Alcohol dehydrogenase/aldehyde dehydrogenase activity ratios (ADH/AlDH) in livers of WP controls were considerably higher than those in EP controls. The difference in ADH/AlDH has somewhat decreased after ethanol treatment. However, this ratio remained the highest in the WP alcohol-treated group. The signs of proteinic and lipid dystrophy of the liver in alcohol-treated WP rats were expressed much more clearly than in all other groups. It is concluded that in the liver of animals with a high ADH/AlDH ratio there are favourable conditions for accumulation of a toxic hepatocyte-damaging acetaldehyde.     

Genetic variation of aldehyde dehydrogenase in primates.

Genetic variation of aldehyde dehydrogenase has been demonstrated in catarrhine primates. The results are in accordance with the formal genetic interpretation: three alleles, AldDH1, AldDH2, AldDH3, at the gene locus AldDH. Obviously, the allele AldDH1 has undergone fixation in Homo and Hylobates, the allele AldDH2 in Macaca and Papio, and the allele AldDH3 in Cercopithecus.     

An intergenic alcohol dehydrogenase isozyme in sunflowers

The isozymes of alcohol dehydrogenase (ADH; E.C. 1.1.1.1) in wild and cultivated sunflower (Helianthus annuus) seeds can be resolved electrophoretically into 12 bands. The slowest- and probably the fastest-migrating sets of three are allozymic products of two genes, Adh ₁ and Adh ₂ , each having two alleles, F (for fast) and S (for slow). Evidence from dissociation-recombination experiments utilizing bands excised from starch gels indicates that an intermediately-migrating isozyme is a dimeric intergenic product consisting of ADH-1F and ADH-2S subunits. The hybrid isozyme was unstable in vitro in that its monomers spontaneously dissociated and recombined to produce ADH-1FF and ADH-2SS isozymes. The molecular weights of the hybrid as well as the parental isozymes were estimated at approximately 98,000.Supported by a Graduate School Research grant of the University of Kansas and by NSF grant GB-35853.     

Tissue specific alcohol dehydrogenase isozyme variation in carrot: Whole plant versus in vitro cultured cells

Summary Tissue specific qualitative variation in the zymmogram profile of alcohol dehydrogenase in carrot is described. Extracts made from roots and petiole tissues of the plant exhibit three and two bands of activity, respectively. No alcohol dehydrogenase (ADH) activity is detectable in lamina extracts. Similar extracts from carrot cells cultured in vitro exhibit five bands of ADH activity. However, when the same cell line is cultured in medium either lacking auxin (2,4-D) or Zn⁺⁺, no ADH activity can be observed on the gels.     

Kinetics and mechanism of the F1 isozyme of horse liver aldehyde dehydrogenase.

The reaction mechanism of the F1 isozyme of horse liver aldehyde dehydrogenase (EC 1.2.1.3) was investigated using both steady-state and rapid kinetic techniques. Using the steady-state substrate velocity patterns, the NADH inhibition patterns at several aldehyde concentrations, and the substrate analog (adenosine diphosphoribose and chloral hydrate) inhibition patterns, the enzymic catalysis was shown to involve ordered addition of NAD followed by aldehyde. This mechanism was confirmed using the kinetics of the hydrolysis of p-nitrophenyl acetate as an indicator of the dehydrogenase substrate binding. Steady-state experiments with deuteroacetaldehyde showed the V to be unchanged, but the K_m increased (). Stopped flow experiments where E-NAD was rapidly mixed with aldehyde showed a burst of NADH formation followed by slower steady-state turnover. This result clearly indicates that the rate limiting step lies after NAD reduction. The NADH off rate (0.7 s^?1) as estimated by displacement of NADH from the E-NADH complex upon rapid addition of NAD was found to be very close to the steady-state site turnover number (0.3 s^?1). This fact and the relatively small effect of aldehyde R-group on maximal velocity suggest that the slow rate of NADH release contributes significantly to limitation of the enzyme catalytic velocity.     

Multifunctionality of liver alcohol dehydrogenase. Studies of aldehyde dehydrogenase activity

Kinetic studies of the liver alcohol dehydrogenase catalyzed dehydrogenation of aldehydes were carried out over a wide range of octanal concentrations. The effect of specific inhibitors of liver alcohol dehydrogenase on aldehyde dehydrogenase activity was examined. The results were consistent with a steady-state random mechanism with the formation of the ternary E · NADH octanal complex at low temperatures. This ternary complex becomes inconspicuous at high temperatures. The aldehyde dehydrogenase activity was found to associate with all ethanol-active isozymes. The dual dehydrogenase reactions are catalyzed by the same molecule, presumably in the region of the same domain. However, the two activities respond differently to structural changes.     

Polymorphism of aldehyde dehydrogenase and alcohol sensitivity

The metabolism of acetaldehyde has received considerable attention in the past years owing to its acute and chronic toxic effects in humans. Aldehyde dehydrogenase (ALDH) catalyzes the oxidation of acetaldehyde in liver and other organs. Two major isozymes of hepatic ALDH (ALDH I or E2 and ALDH II or E1), which differ in their structural and functional properties, have been characterized in humans. The ALDH I with a low Km for acetaldehyde is predominantly of mitochondrial origin and ALDH II which has a relatively higher Km is of cytosolic origin. An inherited deficiency of ALDH I isozyme has been found among Japanese and Chinese which is primarily responsible for producing acute alcohol sensitivity symptoms (flushing response) after drinking mild doses of alcohol. Biochemical, immunochemical and molecular genetics data indicate a structural mutation in the ALDH I isozyme gene responsible for the loss in catalytic activity. Population genetic studies indicate a wide prevalence of this ALDH polymorphism among individuals of Mongoloid race. Flushing response to alcohol shows familial resemblances and preliminary family data from Japan, China and Korea hint to an autosomal codominant inheritance for ALDH I isozyme deficiency. The ALDH polymorphism is apparently responsible for the low incidence of alcoholism in Japanese, Chinese and Koreans. Alcohol-induced sensitivity due to ALDH isozyme deficiency may act as an inhibitory factor against excessive alcohol drinking thereby imparting a protection against alcoholism.     

The intramucosal distribution of gastric alcohol dehydrogenase and aldehyde dehydrogenase activity in rats.

Using qualitative and microquantitative histo-chemical techniques, alcohol dehydrogenase and aldehyde dehydrogenase activity was studied in the gastric mucosa of male and female rats. Alcohol dehydrogenase was demonstrated by staining reactions with maximum activity in surface and neck cells and with clearly weaker activity also in parietal cells. Aldehyde dehydrogenase could be detected in surface and neck cells, and also to a comparable degree in the parietal cells. Quantitative analyses of microdissected samples yielded high values for alcohol dehydrogenase activity exclusively in the superficial part of the gastric mucosa, whereas low-Km aldehyde dehydrogenase activity showed a decreasing gradient from the surface to the deeper parts of the mucosa. Sex differences could not be confirmed.     

Intralobular distribution of rat liver aldehyde dehydrogenase and alcohol dehydrogenase

1. The activity of liver microsomal high Km-ALDH and mitochondrial low Km-ALDH, which may be primarily responsible for the oxidation of acetaldehyde after ethanol administration was found to be predominantly distributed in the centrilobular area. 2. The activities of other ALDH isozymes in mitochondrial and soluble fractions were evenly distributed in periportal and perivenous regions. 3. The activity of ADH which is involved in production of acetaldehyde was predominantly located in the periportal area. 4. From these results it seems unlikely that a concentration of acetaldehyde after ethanol ingestion is higher in perivenous hepatocytes than in periportal ones. Additional data would be needed to understand fully the mechanism by which ethanol induces predominantly centrilobular liver injury.     

Electrophoretic analyses of alcohol dehydrogenase, aldehyde dehydrogenase, aldehyde oxidase, sorbitol dehydrogenase and xanthine oxidase from mouse tissues.

1. Cellulose acetate zymograms of alcohol dehydrogenase (ADH), aldehyde dehydrogenase, sorbitol dehydrogenase, aldehyde oxidase, "phenazine" oxidase and xanthine oxidase extracted from tissues of inbred mice were examined. 2. ADH isozymes were differentially distributed in mouse tissues: A2--liver, kidney, adrenals and intestine; B2--all tissues examined; C2--stomach, adrenals, epididymis, ovary, uterus, lung. 3. Two NAD+-specific aldehyde dehydrogenase isozymes were observed in liver and kidney and differentially distributed in other tissues. Alcohol dehydrogenase, aldehyde oxidase, "phenazine" oxidase and xanthine oxidase were also stained when aldehyde dehydrogenase was being examined. 4. Two aldehyde oxidase isozymes exhibited highest activities in liver. 5. "Phenazine oxidase" was widely distributed in mouse tissues whereas xanthine oxidase exhibited highest activity in intestine and liver extracts. 6. Genetic variants for ADH-C2 established its identity with a second form of sorbitol dehydrogenase observed in stomach and other tissues. The major sorbitol dehydrogenase was found in high activity in liver, kidney, pancreas and male reproductive tissues.     

Variation of transition-state structure as a function of the nucleotide in reactions catalyzed by dehydrogenases. 1. Liver alcohol dehydrogenase with benzyl alcohol and yeast aldehyde dehydrogenase with benzaldehyde

Primary intrinsic deuterium and 13C isotope effects have been determined for liver (LADH) and yeast (YADH) alcohol dehydrogenases with benzyl alcohol as substrate and for yeast aldehyde dehydrogenase (ALDH) with benzaldehyde as substrate. These values have also been determined for LADH as a function of changing nucleotide substrate. As the redox potential of the nucleotide changes from -0.320 V with NAD to -0.258 V with acetylpyridine-NAD, the product of primary and secondary deuterium isotope effects rises from 4 toward 6.5, while the primary 13C isotope effect drops from 1.025 to 1.012, suggesting a trend from a late transition state with NAD to one that is more symmetrical. The values of Dk (again the product of primary and secondary isotope effects) and 13k for YADH with NAD are 7 and 1.023, suggesting for this very slow reaction a more stretched, and thus symmetrical, transition state. With ALDH and NAD, the primary 13C isotope effect on the hydride transfer step lies in the range 1.3-1.6%, and the alpha-secondary deuterium isotope effect on the same step is at least 1.22, but 13C isotope effects on formation of the thiohemiacetal intermediate and on the addition of water to the thio ester intermediate are less than 1%. On the basis of the relatively large 13C isotope effects, we conclude that carbon motion is involved in the hydride transfer steps of dehydrogenase reactions.     

Glycerol-3-phosphate dehydrogenase isozyme variation in insects

Glycerol-3-phosphate dehydrogenase (GPD) serves a central function in the metabolism of carbohydrate for insect flight. This paper reports that the function is supported in a wide range of species by thorax-specific GPD isozymes. These have been discovered in nine of 14 orders in which winged forms have been tested, including all of the major orders except Lepidoptera and Odonata. Examples have been found in each of the Polyneoptera, Paraneoptera and Holometabola, occurring predominantly in larger, stronger fliers which use carbohydrate as a fuel. Thorax-specific GPD isozymes have been found only once (in a tiphiid female) in a flightless insect and in the Palaeoptera not at all.