Publisher Summary This chapter describes the advances with an emphasis on the structures of the alcohol dehydrogenases and the relationship between structure and function Yeast and mammalian alcohol dehydrogenase differ in substrate specificity and rate of catalytic activity The classic yeast enzyme is more specific for acetaldehyde and ethanol, which is consistent with its recognized physiological Significance to participate in alcohol fermentation at the end of the glycolytic pathway Enzyme forms with other functions and properties also occur in yeast The mammalian enzymes have broad substrate specificity and, even with primary alcohols, the maximum activity is not observed with ethanol Alcohols including ethanol, produced in the intestinal tracts mainly by bacterial actions, are found in the portal vein One physiological function of liver alcohol dehydrogenase may be to metabolize these products Structural studies have established that mammalian alcohol dehydrogenases have a distant evolutionary link to both the yeast and bacterial enzymes Ingested alcohol is metabolized to acetaldehyde mainly by the action of liver alcohol dehydrogenase

3 Alcohol Dehydrogenases

Ann. H u m . Genet., Lond. (1971), 34, 251 Printed in Great Britain Developmental changes and polymorphism in human alcohol dehydrogenase BY MOYRA SMITH, D. A. HOPKINSON AND HARRY HARRIS M.R.C. Human Biochemical Genetics Unit, Galton Laboratory, University College London I n man, alcohol dehydrogenase (alcohol: NAD oxidoreductase E.C. 1 . 1 . 1 . 1 ) occurs princi- pally in liver, though low levels of activity have aIso been found in lung, kidney and the gastro- intestinal tract (Moser, Papenberg & von Wartburg, 1968). Evidence for at least three distinct isozymes has been obtained by chromatography of liver extracts on CM cellulose (Blair & Vallee, 1966) and also by electrophoresis (Moser et al. 1968; Pikkarainen & Raiha, 1969; Murray & Motulsky, 1970). Von Wartburg, Papenberg & Aebi (1965) reported that certain individuals have an atypical form of alcohol dehydrogenase associated with an increased level of activity. The usual and atypical forms of the enzyme were shown to differ markedly in pH activity curves with ethanol as substrate. The pH optimum for the usual form was found to be pH 10.8 and for the atypical form pH 8.5. The enzymes also differed in the relative rates at which they oxidized various other alcohols, and in the degree of inhibition produced by various metal binding agents. On the other hand no significant differences were observed in Michaelis constants for the substrates ethanol or acetaldehyde or for the corresponding coenzymes NAD or NADH. Also the pH activity curve with acetaldehyde as substrate was essentially the same for both enzymes, having an optimum at pH 6.0-6.5. A simple screening test to distinguish the usual from the atypical enzyme in crude liver homo- genates was designed (von Wartburg et al. 1965). This involves determining the ratio of the activity at pH 11.0 to that at pH 8-8 with ethanol as substrate under standard conditions. The usual enzyme gives a value for this ratio greater than 1.0, and the atypical enzyme less than 1.0. In a survey of 59 liver samples from different individuals in Switzerland, 12 were found to have the atypical alcohol dehydrogenase, and in another series of 50 individuals from London, 2 were found to be atypical (von Wartburg & Schiirch, 1968). The atypical enzyme occurred in indi- viduals varying from 16 to 82 years of age. Pikkarainen & Raiha (1967) reported that alcohol dehydrogenase activity in liver is low during foetal life and reaches adult levels about 5 years after birth. Changes in electrophoretic pattern have also been noted during development (Pikkarainen & Raiha, 1969; Murray & Motulsky, 1970). In the earliest stages only a single isozyme is observed but later further iso- zymes appear. I n adult liver individual variations in the relative contribution of the different isozymes to the total activity have been noted (von Wartburg & Schiirch, 1968), but no clear electrophoretic differences between the usual and atypical alcohol dehydrogenases as determined by the ratio of activity at pH 11.0 and pH 8.8 were detected. The present paper is concerned with a study of human alcohol dehydrogenase in which liver, lung, kidney and intestinal material from foetuses, infants and adults has been examined. The en- zyme has been investigated both by spectrophotometric assay at different pH’s and by starch-gel

/pdf/developmental-changes-and-polymorphism-in-human-alcohol-174cj3nh0u.pdf

Developmental changes and polymorphism in human alcohol dehydrogenase

Background. The amount of alcohol ingested by a breast-fed infant is only a small fraction of that consumed by its mother, but even this small amount may have an effect on the infant. We investigated whether the ingestion of alcohol by a lactating woman altered the odor of her milk and whether exposure to a small amount of alcohol in the mother's milk had immediate effects on the behavior of the infant. Methods. Twelve lactating women and their infants were tested on two days separated by an interval of one week. On each testing day, the mother expressed a small quantity of breast milk and then drank either orange juice or orange juice containing a small quantity of ethanol (0.3 g per kilogram of body weight). Additional milk samples were obtained at fixed intervals after the ingestion of the beverage and analyzed to determine their ethanol content. The samples were also evaluated by a panel of adults to determine whether any difference in the odor of the milk was detectable after alcohol ingesti...

https://www.nejm.org/doi/pdf/10.1056/NEJM199110033251401

The transfer of alcohol to human milk. Effects on flavor and the infant's behavior.

Breast-feeding is the best method of feeding neonates and young infants.1 Its popularity has increased in recent years,2 although in 1995 only about 60 percent of new mothers in the United States were breast-feeding their infants at the time of hospital discharge.3 Current recommendations suggest that in the absence of contraindications, women should breast-feed their infants for at least the first 12 months of life. However, many mothers are likely to need to take medications at some point during this time.4,5 The possible effects of these medications on breast-fed infants are therefore of great concern. Benefits of Breast-Feeding Breast-feeding . . .

Drug Therapy for Breast-Feeding Women

Over the last decades, significant progress in the fields of perinatal and neonatal medicine has resulted in improved survival of very low and extremely low-birth weight infants. At present, these ...

Guidelines for the establishment and operation of a donor human milk bank.

Extract: In the present study, alcohol dehydrogenase activity (ADH) has been measured in human liver tissue during development, and a comparison made between certain kinetic properties of crude enzyme preparations from fetal and adult liver. The fetal livers were obtained from legal abortions. The liver tissue from children and adults was acquired during surgery of the abdomen in cases where no macroscopic abnormality of the livers was observable. The liver tissue was frozen immediately after excision. Studies indicated that the enzyme activity was stable at −20° for up to 6 days. All the determinations were made within 24 hours of the liver being sampled. A 10% liver homogenate was prepared in ice-cold 0.25 M sucrose containing 1 % Triton X-100. After centrifugation of the homogenate for 10 minutes at 5000 × g at 3°C, samples were taken from the supernatant for protein determination and for enzyme assays. Table I presents the enzyme activity levels in human liver during the development from a fetus to an adult organism. The results are expressed as milliunits per g liver wet weight and per 100 mg soluble liver protein. ADH activity is detectable in 2-month-old fetuses, although it amounts to no more than 3–4: % of adult activity. Activities of adult range are found after 5 years of age. Considerable varation exists in the activity of adult livers. The relationship between pH and the rate of reaction appears in figure 1. The final pH figures of the reaction mixtures are given; these were determined with a Radiometer pH meter. Adult human liver ADH has a pH optimum of about 10.4, and the pH optimum for the fetal enzyme preparations is 10.0. Lineweaver-Burk analyses which illustrate the relationship between the concentration of ethanol and NAD, and the ADH activity in adult and fetal liver are presented in figures 2 and 3. The results presented are typical of three cases studied in each group. Close agreement was found for all constants in the different enzyme preparations examined. The apparent Km values for ethanol were 3400 μM. and 1100 μM, and for NAD 70 μM and 150 μM in fetal and adult enzyme preparations respectively. Speculation: These results do not constitute a foundation for a conclusion whether the fetal and the adult enzyme preparations are composed of a similar isoenzyme pattern. Studies which make use of purified enzyme and isoenzyme preparations are needed. Nevertheless, the results presented here suggest that variants may be found in alcohol dehydrogenase during development.

/pdf/development-of-alcohol-dehydrogenase-activity-in-the-human-4gxmcoh2v7.pdf

Development of alcohol dehydrogenase activity in the human liver.

1. Alcohol-dehydrogenase activity is first detectable in the rat foetus on about the eighteenth day of gestation, after which time it increases to about 25% of the adult activity at birth. Adult activity is reached at about 18 days after birth. The ethanol-oxidizing capacity of liver slices from rats correlates well with the increase of the enzyme activity in vitro. 2. In the guinea pig there is a steady linear increase from about 17 days before term to 5 days after birth. Adult activity is reached between the sixth and eighth postnatal day. 3. Some kinetic properties of liver alcohol dehydrogenase are very similar in newborn and adult rats. 4. Administration of ethanol to pregnant rats during the latter half of gestation had no effect on alcohol-dehydrogenase activity in the liver of the newborn offspring. Intraperitoneal injections of ethanol to newborn and young rats had no effect on the alcohol-dehydrogenase activity of the livers. 5. Intraperitoneal injections of hydrocortisone and triamcinolone to newborn and adult non-adrenalectomized rats had no significant effect on the increase of the alcohol-dehydrogenase activity as studied up to 4 days after the injection.

/pdf/developmental-changes-in-alcohol-dehydrogenase-activity-in-1o8e7cgffp.pdf

P H Pikkarainen

Papers

Development of alcohol dehydrogenase activity in the human liver.

Developmental changes in alcohol-dehydrogenase activity in rat and guinea-pig liver.