Sorbitol Dehydrogenases Research Articles

Dual relationships of xylitol and alcohol dehydrogenases in families of two protein types

Xylitol dehydrogenase encoded by gene XYL2 from Pichia stipitis is a member of the medium-chain alcohol dehydrogenase family, as evidenced by the domain organization and a distant homology (24% residue identity with the human class I γ 1 alcohol dehydrogenase). Much of a loop structure is missing, like in mammalian sorbitol and prokaryotic threonine dehydrogenases, many additional differences occur, and relationships are closest with the sorbitol dehydrogenase, the equivalence of which in P. stipitis may actually be the xylitol dehydrogenase. A second P. stipitis gene, also cloned and corresponding to a xylitol dehydrogenase, is highly different from XYL2, but encodes an enzyme with structural properties typical of the short-chain dehydrogenase family, which also contains an alcohol dehydrogenase (from Drosophila). Thus, yeast xylitol dehydrogenases, like alcohol and polyol dehydrogenases from other sources, have dual derivations, combining similar enzyme activities in separate protein families. In contrast to the situation with the other enzymes, both forms of xylitol dehydrogenase are present in one organism.

Identification of reactive tyrosine residues in cysteine-reactive dehydrogenases Differences between liver sorbitol, liver alcohol and Drosophila alcohol dehydrogenases

Modification of tyrosine residues with tetranitromethane and reversible sulphite protection of cysteine residues were tested on three dehydrogenases of two families. In liver alcohol dehydrogenase no Tyr residue is appreciably labelled, while in the homologous sorbitol dehydrogenase Tyr-109 is specifically labelled; the difference corresponds to a segment correlating with subunit interactions and the different quaternary structures of the proteins. In Drosophila alcohol dehydrogenase. Tyr modification is multiple, and the results show the presence of two different states of Cys residues, reactive in the presence and absence of cupric ions, respectively. Super-activation with cyanide was also noticed after S-sulphocysteine protection. The results demonstrate the possibility of identification of specific Tyr residues in proteins with reversibly protected Cys residues.

Progressive sequence alignment and molecular evolution of the Zn-containing alcohol dehydrogenase family

Sequences of 47 members of the Zn-containing alcohol dehydrogenase (ADH) family were aligned progressively, and an evolutionary tree with detailed branch order and branch lengths was produced. The alignment shows that only 9 amino acid residues (of 374 in the horse liver ADH sequence) are conserved in this family; these include eight Gly and one Val with structural roles. Three residues that bind the catalytic Zn and modulate its electrostatic environment are conserved in 45 members. Asp 223, which determines specificity for NAD, is found in all but the two NADP-dependent enzymes, which have Gly or Ala. Ser or Thr 48, which makes a hydrogen bond to the substrate, is present in 46 members. The four Cys ligands for the structural zinc are conserved except in zeta-crystallin, the sorbitol dehydrogenases, and two bacterial enzymes. Analysis of the evolutionary tree gives estimates of the times of divergence for different animal ADHs. The human class II (pi) and class III (chi) ADHs probably diverged about 630 million years ago, and the newly identified human ADH6 appeared about 520 million years ago, implying that these classes of enzymes may exist or have existed in all vertebrates. The human class I ADH isoenzymes (alpha, beta, and gamma) diverged about 80 million years ago, suggesting that these isoenzymes may exist or have existed in all primates. Analysis of branch lengths shows that these plant ADHs are more conserved than the animal ones and that class III ADHs are more conserved than class I ADHs. The rate of acceptance of point mutations (PAM units) shows that selection pressure has existed for ADHs, implying that these enzymes play definite metabolic roles.

Cysteine reactivity in sorbitol and aldehyde dehydrogenases Differences towards the pattern in alcohol dehydrogenase

In sorbitol dehydrogenase only one cysteine residue, Cys-43, is reactive in both anionic buffer (phosphate) and zinc-liganding buffer (imidazole) upon carboxymethylation. This is in contrast to the situation in the structurally related liver alcohol dehydrogenase, with either of two alternative Cys residues being reactive, and is compatible with differences in zinc-binding and active site relationships between these two metalloenzymes. Unrelated aldehyde dehydrogenase, upon carboxamidomethylation, shows a third pattern, now less well defined but confirming the presence of a thiol function of Cys-302 close to the active site.

Variability within mammalian sorbitol dehydrogenases. The primary structure of the human liver enzyme.

The primary structure of sorbitol dehydrogenase from human liver has been determined by peptide analysis in order to relate the variability of this enzyme to that of the others within the alcohol dehydrogenase family. The structure obtained reveals 355 residues with an acyl-blocked N-terminus and an unexpected microheterogeneity at position 237 (Gln/Leu). The residue identity between sheep and human liver sorbitol dehydrogenase is 89%. This variability is similar to that of class I alcohol dehydrogenases, but distinctly different from that of class III alcohol dehydrogenases, the structures of which are much more conserved. Consequently, class III alcohol dehydrogenase is thus far unique within this family of dehydrogenases, suggesting a particularly strict requirement for that structure. The variability within sorbitol dehydrogenase involves all segments of the molecule but is largely at surface positions and clusters in one such region, covering positions 214-240, corresponding to a segment of the coenzyme-binding domain. Ligands to the active-site zinc and most residues lining the coenzyme-binding and substrate-binding pockets are conserved. However, provided conformational models are reliable, a charge difference may affect the interactions at the inner part of the substrate pocket, another charge difference may affect the interdomain region, and a size difference the adenine pocket. The primary structure of human liver sorbitol dehydrogenase further shows that the absence of three of the four ligands to a second zinc atom present in alcohol dehydrogenases is a general property of sorbitol dehydrogenase.

Variability within mammalian sorbitol dehydrogenases

European Journal of BiochemistryVolume 186, Issue 3 p. 550-550 Free Access Variability within mammalian sorbitol dehydrogenases The primary structure of the human liver enzyme Christina KARLSSON, Search for more papers by this authorWolfgang MARET, Search for more papers by this authorDouglas S. AULD, Search for more papers by this authorJan-Olov HÖÖG, Search for more papers by this authorHans JÖRNVALL, Search for more papers by this author Christina KARLSSON, Search for more papers by this authorWolfgang MARET, Search for more papers by this authorDouglas S. AULD, Search for more papers by this authorJan-Olov HÖÖG, Search for more papers by this authorHans JÖRNVALL, Search for more papers by this author First published: December 1989 https://doi.org/10.1111/j.1432-1033.1989.tb15241.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume186, Issue3December 1989Pages 550-550 RelatedInformation

Roles of Four Sorbitol Related Enzymes and Invertase in the Seasonal Alteration of Sugar Metabolism in Apple Tissue

Abstract Activities and roles of 4 sorbitol enzymes, sorbitol-6-P dehydrogenase, NAD+-dependent sorbitol dehydrogenase, NADP+-dependent sorbitol dehydrogenase and sorbitol oxidase, and acid invertase in apple (Malus domestica Borkh. ‘Jonnagold’) leaves and fruit were studied. Almost all of the soluble carbohydrates in leaves are present as sorbitol throughout the season. Sorbitol-6-P dehydrogenase had the highest activity among the enzymes, being high in young leaves and decreasing with age; whereas NAD+- and NADP+-dependent sorbitol dehydrogenases and sorbitol oxidase activities were barely detectable. Sorbitol was translocated from leaves to fruits where it was readily metabolized to other sugars, so the sorbitol concentration did not increase. NAD+-dependent sorbitol dehydrogenase that converts sorbitol to fructose had the highest activity of the 4 enzymes in developing fruits. Its activity rose in June, decreased in midseason, and increased again with fruit maturation. The fluctuation in enzyme activity corresponded to changes in fructose concentration. Sorbitol oxidase activity, which was about one-fifth that of NAD+-dependent sorbitol dehydrogenase, increased proportionately as fruits enlarged. Acid invertase activity was distinctly higher than sorbitol enzyme activities in both leaves and fruit, but its roles in sugar translocation and metabolism were not clearly established. The levels of sorbitol in stems and peduncles remained relatively constant during the season indicating that little metabolism occurred in the phloem during transit.

Molecular aspects of functional differences between alcohol and sorbitol dehydrogenases

The amino acid sequence of sheep liver sorbitol dehydrogenase has been fitted to the high-resolution model of the homologous horse liver alcohol dehydrogenase by computer graphics. This has allowed construction of a model of sorbitol dehydrogenase that provides explanations why sorbitol is not a substrate for alcohol dehydrogenase, why ethanol is not a substrate for sorbitol dehydrogenase, and what determines its specificity for polyols. An important feature of the model is that one of the ligands to the active site zinc atom is a glutamic acid residue instead of a cysteine residue, which is the corresponding ligand in the homologous alcohol dehydrogenases. This is one component of the structural change that can be related to the different substrate specificities, showing how altered enzymic activity might be brought about by structural changes of the kind that it is now possible to introduce by site-directed mutagenesis and recombinant DNA techniques.

Acetyl-blocked N-terminal structures of sorbitol and aldehyde dehydrogenases

Two new dehydrogenase structures, the 354-residue polypeptide chain of sorbitol dehydrogenase (from sheep liver) and the 500-residue polypeptide chain of cytoplasmic aldehyde dehydrogenase (from human liver), have blocked N-termini. The N-terminal peptides were purified by reverse-phase high-performance liquid chromatography and submitted to mass spectrometry after derivatization. They were also analyzed by dipeptidyl carboxypeptidase digestion, utilizing gas chromatography-mass spectometry for dipeptide identifications. Results are consistent and establish that sorbitol dehydrogenase has N-terminal acetylalanine and aldehyde dehydrogenase N-terminal acetylserine in amino acid sequences that are compatible with estimates from chemical analyses. The two N-terminal residues found are typical of acetylated proteins in general, extend the group of known acetylated dehydrogenases, and show that these intracellular proteins are frequently N-terminally acetylated.

Extended superfamily of short alcohol-polyol-sugar dehydrogenases: structural similarities between glucose and ribitol dehydrogenases

The recently determined primary structure of glucose dehydrogenase from Bacillus megaterium was scanned by computerized comparisons for similarities with known polyol and alcohol dehydrogenases. The results revealed a highly significant similarity between this glucose dehydrogenase and ribitol dehydrogenase from Klebsiella aerogenes. Sixty-one positions of the 262 in glucose dehydrogenase are identical between these two proteins (23% identity), fitting into a homology alignment for the complete polypeptide chains. The extent of similarity is equivalent to that between other highly divergent but clearly related dehydrogenases (two zinc-containing alcohol dehydrogenases, 25% sorbitol and zinc-containing alcohol dehydrogenases, 25%; ribitol and non-zinc-containing alcohol dehydrogenases, 20%), and suggests an ancestral relationship between glucose and ribitol dehydrogenases from different bactera. The similarities fit into a previously suggested evolutionary scheme comprising short and long alcohol and polyol dehydrogenases, and greatly extend the former group to one composed of non-zinc-containing alcohol-polyol-glucose dehydrogenases.

Niridazole-induced biochemical changes in the rat testis

A high dose of niridazole administered intraperitoneally (i.p.) to male rats over a period of 9 weeks induced alterations in the concentrations and activities of some important testicular constituents and enzymes, respectively. The concentrations of total and free cholesterol were higher than those of control animals but the concentration of esterified cholesterol was significantly lower than that of the control rats. Zinc concentration in the testis and prostate gland of niridazole-treated animals was significantly lower than in the control animals. Decreases in the activities of the following enzymes occurred in the testes of niridazole-treated rats: lactate and sorbitol dehydrogenases, aspartate and alanine aminotransferases and alkaline phosphatase. By contrast, there were increases in the activities of testicular malate dehydrogenase and prostate acid phosphatase of rats given niridazole.

The effect of Escherichia coli endotoxins and adrenocortical hormones on plasma enzyme activities in the domestic fowl

The intravenous injection of endotoxins isolated from Escherichia coli serogroups O111 and O78 (2 mg/kg) increased the activities of aspartate transaminase and lactate and sorbitol dehydrogenases in the plasma of six- to 11-week-old chickens during the next 24 h. These changes were compared with those produced by adrenocorticotrophic hormone and beta-methasone and were attributed to tissue damage involving the liver followed by increased enzyme synthesis which may have been induced partly by adrenocortical hormones. Further evidence of liver damage was provided by a fall in the activity of cholinesterase. The alkaline phosphatase activity gave no indication of cholestasis.

A comparison of selected physical properties of hepatic sorbitol dehydrogenases [ l-iditol: NAD oxidoreductases] from four mammalian species

1. 1. The sorbitol dehydrogenases [ l-iditol: NAD oxidoreductase] from livers of cow, man, rat and sheep each possess molecular weights of about 140,000. The beef, rat and sheep liver enzymes are composed of subunits of molecular weight 40,000. 2. 2. The sorbitol dehydrogenases from livers of these four species each possess an isoelectric point of 7.3. 3. 3. The four enzyme preparations show identical mobilities upon disc-gel electrophoresis and yield a single band of enzymic activity. 4. 4. Sorbitol dehydrogenase activity is activitated by the presence of ampholines or by increasing ionic strengths, with maximal activation at about 0.5 M salt concentration. These factors may cause the K m for NAD to be lowered.

Prevention of praseodymium-induced hepatotoxicity by silybin

In rats, the hepatotoxicity of praseodymium nitrate was prevented by treatment with silybin, the main component of silymarin, a compound isolated from Silybum marianum (L.) Gaertn. A single dose (100 mg/kg) of silybin, given 1 hr before or up to 8 hr after praseodymium, almost normalized the serum activities of glutamic pyruvic and oxaloacetic transaminases, sorbitol, and glutamic dehydrogenases, as well as the content of hepatic triglycerides. When administered 17 or 24 hr after the rare earth metal, the protective action of silybin was no longer significant. The hepatocytic changes elicited by praseodymium (endoplasmic reticulum fragmentation and dilatation, massive smooth endoplasmic reticulum proliferation and lipid droplet accumulation) were also prevented by silybin. In correlation with the biochemical parameters, the morphologic alterations were not influenced by silybin when administered 17 or 24 hr after praseodymium.

A Review of Factors Affecting Blood Biochemistry in the Pig

SUMMARY Lack of information on the clinical biochemistry of the conventional pig compared with many other species is due, among other factors, to the present economic policy of culling or isolating unthrifty animal's without preliminary biochemical investigation, and the animal's intractability which makes blood and urine sampling difficult. This paper discusses the effects of some normal environmental factors such as age, sex, breed and particularly diet, as well as some disease conditions, on the levels of some organic serum components such as protein, urea, cholesterol, certain enzymes including alkaline phosphatase, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, glutamate and sorbitol dehydrogenases, arginase, carbamoyl transferase and lactate dehydrogenase, several of which are in current use in the diagnosis of liver disease and muscle dystrophy in other species. Bromsulphthalein clearance and urine analysis for common abnormalities are also discussed. It is concluded, on somewhat slender evidence, and taking into account the effects of age, diet, etc., that liver function can best be assessed routinely by S-GOT, OCT, possibly LDH and to a lesser degree by S-GPT, and kidney function by analysis of urine for abnormalities, and blood or serum for urea. Limited work indicates the possible value of BSP clearance for liver function, but intractability of the species renders this less useful as a routine test. Estimations of serum proteins and cholesterol do not appear to offer much useful information in assessing liver and kidney function. It is concluded that further basic studies must be carried out, more specifically on alkaline phosphatase, glutamate and sorbitol dehydrogenases in order to make it possible to recommend a larger battery of routine tests for liver function, and that estimations of serum urea, urinary protein and phenolsuiphonphthalein clearances should be investigated in connection with kidney function.

Dehydrogenase activities in human and mouse serum using an ultramicro colorimetric analytical system

1. 1. An ultramicro colorimetric system for the analysis of dehydrogenases is presented. The assays are based on the ultimate transfer of electrons from the substrates to a tetrazolium dye. 2. 2. The system was calibrated using reduced nicotinamide adenine dinucleotide as a standard. 3. 3. The 3 enzymes studied were lactate, malate, and sorbitol dehydrogenases using, except for substrate solutions, common reagents for the 3 assays. 4. 4. Normal values found in human and mouse sera obtained with the system were compared using human sera with elevated values as enzyme sources.

Enzyme des fructosestoffwechsels: Enzymaktivitäten in der dünndarmmukosa verschiedener laboratoriumstiere

1. 1. The enzyme level of fructose metabolism was measured in the whole small-intestinal mucosa in rats, golden hamsters, guinea-pigs and rabbits. These enzymes are: ketohexokinase, aldolase, triokinase, aldehyde dehydrogenase, alcohol dehydrogenase, alcohol dehydrogenase (NADP), glycerate kinase and glycerol kinase. Sorbitol dehydrogenases and hexose diphosphatase were also measured. 2. 2. The results prove that the metabolism of fructose of the intestinal mucosa is the same as in liver and kidney. 3. 3. The activity of ketohexokinase and aldolase with substrate fructose-1-phosphate is extremely low in rats in comparison with golden hamsters, guinea-pigs and rabbits. Therefore, the transformation of fructose to glucose is rather poor during passage through the intestinal wall in rats. 4. 4. The activity of sorbitol dehydrogenases of the intestinal mucosa in rabbits and guinea-pigs in high. In rats and golden hamsters, only traces were found.

The Comparative Histochemistry of some Hydrolytic and Oxidative Enzymes in the Livers of Several Domestic and Laboratory Animals

The distribution of various hydrolytic and oxidative enzymes was studied histochemically in the livers of rats, mice, dogs, cats, and cattle. The enzymes investigated comprised non-specific alkaline phosphatase, adenosine triphosphatase, glucose-6-phosphatase, succinic tetrazolium reductase, DPN diaphorase, glutamic, lactic and sorbitol dehydrogenases. The comparative merits of 2 techniques for the demonstration of succinic tetrazolium reductase were evaluated. It was found that the optimal incubation period for the demonstration of adenosine triphosphatase in the canaliculi of dog liver was considerably in excess of that required for the other species investigated.

Enzymes of fructose metabolism in human liver.

The enzyme activities involved in fructose metabolism were measured in samples of human liver. On the basis of U/g of wet-weight the following results were found: ketohexokinase, 1.23; aldolase (substrate, fructose-1-phosphate), 2.08; aldolase (substrate, fructose-1,6-diphosphate), 3.46; triokinase, 2.07; aldehyde dehydrogenase (substrate, D-glyceraldehyde), 1.04; D-glycerate kinase, 0.13; alcohol dehydrogenase (nicotinamide adenine dinucleotide [NAD]) substrate, D-glyceraldehyde), 3.1; alcohol dehydrogenase (nicotinamide adenine dinucleotide phosphate [NADP]) (substrate, D-glyceraldehyde), 3.6; and glycerol kinase, 0.62. Sorbitol dehydrogenases (25.0 U/g), hexosediphosphatase (4.06 U/g), hexokinase (0.23 U/g), and glucokinase (0.08 U/g) were also measured. Comparing these results with those of the rat liver it becomes clear that the activities of alcohol dehydrogenases (NAD and NADP) in rat liver are higher than those in human liver, and that the values of ketohexokinase, sorbitol dehydrogenases, and hexosediphosphatase in human liver are lower than those values found in rat liver. Human liver contains only traces of glycerate kinase. The rate of fructose uptake from the blood, as described by other investigators, can be based on the activity of ketohexokinase reported in the present paper. In human liver, ketohexokinase is present in a four-fold activity of glucokinase and hexokinase. This result may explain the well-known fact that fructose is metabolized faster than glucose.

Preparation of specifically labeled D-fructose-14C1.

A method is described whereby specifically labeled D-fructose-14C can be prepared easily and in high yield (95%) from specifically labeled D-glucose-14C by the action of purified bacterial sorbitol dehydrogenases.