Showing papers on "Aldehyde dehydrogenase published in 1984"

Molecular abnormality of an inactive aldehyde dehydrogenase variant commonly found in Orientals

Abstract: Usual human livers contain two major aldehyde dehydrogenase [(ALDH) aldehyde:NAD+ oxidoreductase] isozymes--i.e., a cytosolic ALDH1 component and a mitochondrial ALDH2 component--whereas approximately equal to 50% of Orientals are "atypical" and have only the ALDH1 isozyme and are missing the ALDH2 isozyme. We previously demonstrated that atypical livers contain an enzymatically inactive but immunologically crossreactive material (CRM) corresponding to the ALDH2 component. The enzymatically active ALDH2 obtained from a usual liver and the CRM obtained from an atypical liver were reduced, S-carboxymethylated, and digested by trypsin. Separation of their digests by high-performance reverse-phase chromatography and by two-dimensional paper chromatography and electrophoresis revealed that ALDH2 contained a peptide sequence of -Glu-Leu-Gly-Glu-Ala-Gly-Leu-Gln-Ala-Asn-Val-Gln-Val-Lys- and that the glutamine adjacent to lysine was substituted by lysine in CRM. All other tryptic peptides, including eight peptides containing S-carboxymethylcysteine, were common in ALDH2 and CRM. It is concluded that a point mutation in the human ALDH2 locus produced the glutamine leads to lysine substitution and enzyme inactivation.

Role of Aldehyde Dehydrogenase in Cyclophosphamide-resistant L1210 Leukemia

Abstract: A cyclophosphamide-resistant L1210 cell line has been shown to have unusually high aldehyde dehydrogenase activity. The sensitivity of this cell line to 4-methylcyclophosphamide and phosphoramide mustard in vivo and corresponding sensitivities in vitro indicate that 4-hydroxycyclophosphamide and/or aldophosphamide is the form in which cyclophosphamide reaches these tumor cells in mice and that intracellular aldehyde dehydrogenase activity is an important determinant of cyclophosphamide sensitivity in these leukemia cell lines.

Aldehyde dehydrogenase from human liver: primary structure of the cytoplasmic isoenzyme

Abstract: Analysis of CNBr fragments and other peptides from human liver cytoplasmic aldehyde dehydrogenase enabled determination of the complete primary structure of this protein The monomer has an acylated amino terminus and is composed of 500 amino acid residues, including 11 cysteine residues No evidence of any microheterogeneity was obtained, supporting the concept that the enzyme is a homotetramer The disulfiram-sensitive thiol in the protein, earlier identified through its reaction with iodoacetamide, is contributed by a cysteine residue at position 302, while the cysteine which in horse liver mitochondrial aldehyde dehydrogenase is reactive with coenzyme analogs appears to correspond to either Cys-455 or Cys-463 Analysis of glycine distribution and prediction of secondary structures to localize βαβ regions typical for coenzyme-binding are not fully unambiguous, but suggest a short region around position 245 as a likely segment for this function In this region, sequence similarities to parts of a bacterial aspartate-β-semialdehyde dehydrogenase and a mammalian alcohol dehydrogenase were noted Otherwise, no extensive similarities were detected in comparisons with characterized mammalian enzymes of similar activity or subunit size as aldehyde dehydrogenase (glyceraldehyde-3-phosphate dehydrogenase and glutamate dehydrogenase, respectively)

Inhibition of Etoposide-induced DNA Damage and Cytotoxicity in L1210 Cells by Dehydrogenase Inhibitors and Other Agents

Abstract: The mechanism of action of 4'-demethylepipodophyllotoxin-9-(4,6-O-ethylidene-beta-D-glucopyra noside) (VP-16), an important antitumor agent, is unclear There is evidence that DNA may be the target of action because VP-16 causes single-strand and double-strand breaks in DNA and produces cytotoxicity over a similar dose range We have hypothesized that an enzyme system, such as dehydrogenase, catalyzes an oxidation-reduction reaction involving the pendant phenolic group which forms an active metabolite that causes the DNA damage and cytotoxicity To test our hypothesis, we investigated the effect of disulfiram, an aldehyde dehydrogenase inhibitor, and its metabolite, diethyldithiocarbamate, on VP-16-induced DNA damage in L1210 cells Using the alkaline elution technique to assay DNA damage, we found that disulfiram and diethyldithiocerbamate inhibited VP-16-induced single-strand breaks Both compounds were also capable of significantly reducing VP-16-induced cytotoxicity Oxalic acid, pyrophosphate, and malonic acid, competitive inhibitors of succinate dehydrogenase, and the naturally occurring dehydrogenase substrates, succinic acid, beta-glycerophosphate, and isocitric acid, also blocked the effects of VP-16 Free-radical scavengers were also studied While sodium benzoate was particularly effective in preventing drug-induced DNA damage and cytotoxicity, a number of other scavengers were not Our data are consistent with the hypothesis that VP-16 is activated by an enzyme such as a dehydrogenase which transforms it into an active intermediate resulting in DNA damage and, consequently, cell death

Erythrocyte aldehyde dehydrogenase activity in alcoholism

Abstract: Erythrocyte aldehyde dehydrogenase activity was determined in 44 chronic alcoholic patients within 18-36 hr after discontinuation of chronic alcohol intake and in 20 nonalcoholic controls. The enzyme activity was decreased to 4.98 +/- 0.52 mlU/mg of protein in the alcoholics as compared with a value of 8.25 +/- 1.29 mlU/mg of protein in the controls (p less than 0.05). The level of the enzyme activity did not correlate significantly with the daily quantity of alcohol consumption or the degree of liver injury reflected in elevations of serum aspartate aminotransferase. Repeat determination in 23 of the alcoholics after 2 weeks of supervised abstinence in an inpatient unit resulted in an increase in the enzyme activity to control levels. These findings show that the decreased activity of erythrocyte aldehyde dehydrogenase which occurs in association with alcohol ingestion is not an inherent characteristic of alcoholism.

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.

Abstract: 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.

Accumulation of acetaldehyde in alcohol-sensitive Japanese: relation to ethanol and acetaldehyde oxidizing capacity.

Abstract: The metabolism of ethanol and its oxidation product, acetaldehyde, was studied in Japanese volunteers. Subjects who responded by facial flushing and tachycardia were found to accumulate acetaldehyde during ethanol intoxication, in contrast to the near absence of blood acetaldehyde in nonflushing subjects. There were large individual variations in acetaldehyde accumulation observed in the former group, and this accumulation correlated well with the intensity of the physiological responses, but not with rate of ethanol elimination. Oral pretreatment with the alcohol dehydrogenase inhibitor, 4-methylpyrazole, reduced ethanol elimination by 15-25% and strongly suppressed acetaldehyde accumulation. However, here too there was no relation between individual ethanol elimination rate and acetaldehyde accumulation. Furthermore, the change in the blood lactate/pyruvate concentration ratio after ethanol intake was apparently unrelated to the degree of acetaldehyde accumulation. These results, combined with our previous observation of a strong negative correlation between increase in heart rate and activity of cytosolic aldehyde dehydrogenase in erythrocytes, suggest that in flushing Orientals lacking the low-Km aldehyde dehydrogenase isozyme, the alternative cytosolic enzyme is responsible for acetaldehyde oxidation, and its activity probably determines the individual variation of acetaldehyde-mediated physiological responses.

Regulation of aldehyde dehydrogenase activity in five rat hepatoma cell lines.

Abstract: Significant changes in aldehyde dehydrogenase (ALDH) activity occur during rat hepatocarcinogenesis in vivo. An NADP-dependent tumor ALDH isozyme has been studied extensively. To better understand the nature, origin, and importance of this tumor-associated phenotypic change, we have examined the ALDH activity of five well-established rat hepatoma cell lines, H4-II-EC3, HTC, McA-RH7777, JM1, and JM2. HTC, JM1, and JM2 express the tumor ALDH phenotype, as indicated by elevated NADP-dependent, benzaldehyde-oxidizing activity, the appearance of new isozymes by electrophoresis, and characteristic histochemical localization of ALDH activity in situ. The tumor ALDH phenotype is not detected in McA-RH7777 cells. H4-II-EC3 has intermediate tumor ALDH activity. Thus, the 5 cell lines provide a spectrum of tumor ALDH activities representative of the range of activities seen in vivo. Benzo(a)pyrene, 3-methylcholanthrene, and phenobarbital induce hepatic ALDH activity after treatment in vivo. The ability of these compounds to induce ALDH in vitro was assessed in H4-II-EC3, McA-RH7777, HTC, JM1, and JM2. Treatment of cell cultures for 72 hr with 3-methylcholanthrene (1.0 mm) increases the NADP-dependent ALDH activity in H4-II-EC3 and McA-RH7777 cell lines up to 34- and 11-fold, respectively. Treatment with benzo(a)pyrene (1.0 mm) also increases the NADP-dependent ALDH activity in both lines up to 17- and 48-fold, respectively. Treatment with 3-methylcholanthrene or benzo(a)pyrene increases ALDH activity 2-fold in HTC and JM2 but does not increase NADP-dependent ALDH activity in JM1. Only marginal increases in NADP-dependent ALDH are observed after phenobarbital treatment in 4 of 5 cell lines. The induction of ALDH is blocked by actinomycin D, α-amanitin, and cycloheximide. These studies support our hypothesis that changes in ALDH activity observed in vivo are due to mutational events occurring in initiated cells. It appears that rat hepatoma cell lines will provide an in vitro model for studying genetic regulation of the tumor ALDH.

Expression of tumor-associated aldehyde dehydrogenase during rat hepatocarcinogenesis using the resistant hepatocyte model

Abstract: The resistant hepatocyte model was used to study expression of tumor-associated aldehyde dehydrogenase (ALDH) activity during the course of rat hepatocarcinogenesis. The hepatic ALDH phenotype was determined at intervals over 280 days by histochemical analysis, total ALDH activity assays and gel electrophoresis, using propionaldehyde and NAD (P/NAD) to characterize normal liver ALDH activity or benzaldehyde and NADP (B/NADP) to determine tumor-associated ALDH activity. By total activity assays and gel electrophoresis, no significant changes in ALDH activity occurred until day 70. However, histochemical analysis clearly demonstrated changes in ALDH activity early in neoplastic development. Intense focal hepatocyte staining with P/NAD and/or B/NADP was first detectable at day 28. The number of P/NAD-positive foci increased until day 35 then declined until day 70. The number of B/NADP-positive foci also increased until day 35, but then remained relatively constant for the remainder of the experiment. GGT activity of serial sections indicated that early ALDH-positive lesions represent a small subpopulation (9%) of all GGT-positive foci. However, by day 168 a significant portion (80%) of persistent GGT-positive neoplastic nodules were also B/NADP-positive histochemically. In addition, virtually all hepatocellular carcinomas (96%) generated by this protocol possessed significantly elevated levels of tumor-associated ALDH by histochemical analysis, total ALDH activity and gel electrophoresis. These results indicate that early appearing ALDH-positive lesions may define one early subpopulation of all initiated cells that have a high probability of progressing to the ultimate neoplasm.

Higher correlation of ethanol consumption with brain than liver aldehyde dehydrogenase in three strains of rats

Abstract: Voluntary ethanol consumption and high Km (mM range) brain and liver aldehyde dehydrogenase (ALDH) activity were measured in male rats of the Long-Evans, Wistar and Sprague-Dawley strains. The total amounts of ethanol consumed by the three strains did not differ significantly, nor did the levels of cerebral ALDH activity. Levels of brain ALDH did not differ as a function of ethanol exposure and across strains. Levels of ethanol consumption correlated better with levels of brain than liver aldehyde-oxidizing capacity, which were tested separately for each strain and also combining all the animals. Inherent variation in brain ALDH may be a biochemical counterpart of observed differences in voluntary ethanol intake within strains.

The induction of cytochrome P-450 in the alkane-utilizing yeast Lodderomyces elongisporus: Alterations in the microsomal membrane fraction

Abstract: The adaptation of Lodderomyces elongisporus cells to n-alkane utilization was found to be connected with several alterations in the enzyme pattern of the whole cell and the microsomal fraction in particular. A strong induction was found for the microsomal localized cytochrome P-450 alkane hydroxylase system and other enzymes which are directly involved in the terminal degradation pathway of n-alkanes (long-chain alcohol and aldehyde dehydrogenases, catalase). The decrease of the pO2 in the medium enhances the concentration of the constituents of the alkane hydroxylase system as well as that of several other haemoproteins (catalase, cytochrome oxidase), while the long-chain alcohol and aldehyde dehydrogenase enzymes are probably unaffected.

Distribution and properties of aldehyde dehydrogenase in regions of rat brain

Abstract: NAD-dependent aldehyde dehydrogenases (EC 1.2.1.3) were isolated from various subcellular organelles as well as from different regions of rat brain. The mitochondrial, microsomal, and cytosolic fractions were found to contain 40%, 28%, and 12%, respectively, of the total aldehyde dehydrogenase (5.28 +/- 0.44 nmol NADH/min/g tissue) found in rat brain homogenate when assayed with 70 muM propionaldehyde at pH 7.5. The total activity increased to 17.3 +/- 2.7 nmol NADH/min/g tissue when assayed with 5 mM propionaldehyde. Under these conditions the three organelles contained 49%, 23%, and 9%, respectively, of the activity. The enzyme isolated from cytosol possessed the lowest Km. The molecular weight of the enzyme isolated from all three subcellular organelles was approximately 100,000. Four activity bands were found by electrophoresis of crude homogenates, isolated mitochondria, or microsomes on cellulose acetate strips. Cytosol possessed just two of the forms. The total activity was essentially the same in homogenates obtained from cortex, subcortex, pons-medulla, or cerebellum. Further, the enzyme had the same molecular distribution and total activity in each of these four brain regions. Disulfiram was found to be an in vivo and in vitro inhibitor of the enzymes obtained from these brain regions. Mercaptoethanol, required for the stability of the enzyme, reversed the inhibition produced by disulfiram. The effect was greater for enzyme isolated from cytosol than from mitochondria. Calculations led to the prediction that aldehydes such as acetaldehyde are oxidized in cytosol.

Interrelationships between the enzymes of ethanolamine metabolism in Escherichia coli.

Abstract: SUMMARY: The activities of the enzymes ethanolamine ammonia-lyase, CoA-dependent and CoA-independent aldehyde dehydrogenases, and isocitrate lyase were assayed in Escherichia coli which had been grown on various sources of carbon and nitrogen. Induction of ethanolamine ammonia-lyase and of maximal levels of both aldehyde dehydrogenases required the concerted effects of ethanolamine and vitamin (or coenzyme) B12. Molecular exclusion chromatography revealed that, in the absence of one or both co-inducers, two repressible isoenzymes of CoA-dependent aldehyde dehydrogenase (mol. wts 900000 and 120000) were produced, these being replaced by two inducible isoenzymes (mol. wts 520000 and 370000) in the presence of both co-inducers. A similar inducible repressible series of isoenzymes was also observed for CoA-independent aldehyde dehydrogenase. No evidence was found for structural relationships between ethanolamine ammonia-lyase, CoA-dependent aldehyde dehydrogenase and CoA-independent aldehyde dehydrogenase, but mutant and physiological studies demonstrated that the induction of the first two enzymes is under common control. Evidence is presented for the operation of a previously unreported pathway of ethanolamine metabolism in E. coli.

Biochemical genetics of aldehyde dehydrogenase isozymes in the mouse: evidence for stomach- and testis-specific isozymes.

Abstract: Electrophoretic and activity variants have been observed for stomach and testis aldehyde dehydrogenases, respectively, among inbred strains of the house mouse (Mus musculus). Genetic evidence was obtained for two new loci encoding these isozymes (designated Ahd-4 and Ahd-6, respectively, for the stomach and testis isozymes) which segregated independently of a number of mouse gene markers, including Ahd-1 (encoding mitochondrial aldehyde dehydrogenase) on chromosome 4, ep (pale ears), a marker for chromosome 19, on which Ahd-2 (encoding liver cytosolic aldehyde dehydrogenase) has been previously localized, and Adh-3 (encoding the stomach-specific isozyme of alcohol dehydrogenase) on chromosome 3. Recombination studies have indicated, however, that Ahd-4 and Ahd-6 are distinct but closely linked loci on the mouse genome. An extensive survey of the distribution of Ahd-1, Ahd-2, Ahd-4, and Ahd-6 alleles among 56 strains of mice is reported. No variants have been observed, so far, for the microsomal (AHD-3) and mitochondrial/cytosolic (AHD-5) isozymes previously described. This study, in combination with previous investigations on mouse aldehyde dehydrogenases, provides evidence for six genetic loci for this enzyme.

Acetaldehyde utilization and toxicity in Drosophila adults lacking alcohol dehydrogenase or aldehyde oxidase.

Abstract: Metabolic utilization and toxicity of acetaldehyde were studied in flies lacking alcohol dehydrogenase (ADH), aldehyde oxidase (AO), or both functions. Prior to the experiments, mutant alleles Adhn4 and mal were transferred to the same genetic background by 10 successive backcrosses. By comparison with wild-type flies, various deleterious, pleiotropic effects could be attributed to the mal allele but not to Adhn4. Of the four genotypes studied (mal, Adhn4, mal Adhn4, and wild), all were able to use acetaldehyde as a resource in a similar way. In spite of its high toxicity, acetaldehyde appeared a better resource than ethanol. Flies treated with intermediate acetaldehyde concentrations (around 0.5%) exhibited a very high interindividual heterogeneity which could reflect a physiological adaptation occurring as a consequence of the aldehyde treatment. Toxicity tests showed that ADH-negative flies were more sensitive to acetaldehyde than wild type, but this is most likely explained by the transformation of the aldehyde into alcohol. Our results show that the aldehyde metabolizing enzyme (AME) system in Drosophila is neither ADH nor AO. The existence of an aldehyde dehydrogenase is plausible.

Aldehyde dehydrogenase isozyme deficiency and alcohol sensitivity in four different Chinese populations.

Abstract: Four different populations of China were studied regarding aldehyde dehydrogenase isozyme variation and incidence of alcohol sensitivity. While Korean and Mongolian minorities in the north showed an i

Electrophoretic analyses of alcohol dehydrogenase, aldehyde dehydrogenase, aldehyde reductase, aldehyde oxidase and xanthine oxidase from horse tissues

Abstract: 1. 1. Cellulose acetate zymograms of alcohol dehydrogenase (ADH), aldehyde dehydrogenase (AHD), aldehyde reductase (AHR), aldehyde oxidase (AOX) and xanthine oxidase (XOX) extracted from horse tissues were examined. 2. 2. Five ADH isozymes were resolved: three corresponded to the previously reported class I ADHs (EE, ES and SS) (Theorell, 1969); a single form of class II ADH (designated ADH-C2) and of class III ADH (designated ADH-B2) were also observed. The latter isozyme was widely distributed in horse tissues whereas the other enzymes were found predominantly in liver. 3. 3. Four AHD isozymes were differentially distributed in subcellular preparations of horse liver: AHD-1 (large granules); AHD-3 (small granules); and AHD-2, AHD-4 (cytoplasm). AHD-1 was more widely distributed among the horse tissues examined. Liver represented the major source of activity for most AHDs. 4. 4. A single additional form of NADPH-dependent AHR activity (identified as hexonate dehydrogenase), other than the ADHs previously described, was observed in horse liver. 5. 5. Single forms of AOX and XOX were observed in horse tissue extracts, with highest activities in liver.