Alcohol Dehydrogenases from Other Sources

In higher organisms, isozymes frequently have different organal distributions (62,66,471). In this respect, the retinal alcohol dehydrogenase was of special interest because of its possible role in conversion of retinene (1,473). The retinal enzyme, however, apparently lacks this capacity and is different from the liver enzyme (81,474). ADH also occurs in other organs outside the liver (62,66,476,476). Different intracellular distributions of isozymes (477) and an isozyme dependency on the culture medium (478) are also known for other species than the Saccharomyces (Section III,A). Completely (Section IV,C 479) or partially (480) ADH-deficient mutants are known in some species. 

Alcohol dehydrogenase has been studied in several bacteria. Apart from work cited in Sund and Theorell (1), the following sources may be mentioned Clostridium acetobutylicum (481), Escherichia coli (482), 

Leuconostoc mesenteroides (4 3), Pseudomonas aeruginosa (4 4), Streptococcus mutans (435), and Bacillus stearothermophilus (486,437). The protein from the latter species was purified by Kolb and Harris (436) and found to have a free N-terminus in contrast to the liver and yeast alcohol dehydrogenases. The bacterial protein was, therefore, submitted to sequence analysis in an automatic sequenator which revealed the 45 first residues (IS). These are listed in Table XIV. It is clear that the structure of the bacterial enzyme is distantly related to those of the yeast and mammalian enzymes, but few residues are identical in all proteins at equivalent positions (Table XIV). Further aspects of this relationship are discussed in Section II,D. 

Different species of higher plants contain ADH. The peanut enzyme has been purified and shown to be a zinc metalloenzyme (488). From tea seeds a mixture of two isozymes of molecular weight 150,000 have been purified and foimd to be unstable in the absence of thiols (439). Partially purified pea ADH is also unstable (490). Other species in which the enzyme is present, apart from those previously reviewed (1), include oats (491), barley (493), and wheat (493). The occurrence of isozymes has been noticed in wheat (494)  

Several genetic and structural studies have been performed on maize ADH. Alleles at two different genes exist for the enzyme in this species (495-499). The level of activity in the scutellum of maize is controlled 

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The horse liver alcohol dehydrogenase, crystallized by my collaborators Bonnichsen and Wassen in 1948, has been subject to much work the last 20 years, both in my lab and others. Its amino acid sequence (374 residues per subunit = molecule) was cleared up by my young collaborator Hans Jornvall working with I. J. Harris in Cambridge from 1967 and then with us in Stockholm. Alcohol dehydrogenases from other sources were also studied in our and many other peoples laboratories. It is at present one of the most intensively studied enzymes in the world. 

In addition to the alcohol dehydrogenases mentioned above, ADHs from various other sources were examined, especially with respect to increased stability, resistance to organic solvents, and catalytic properties. 

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