Liver alcohol dehydrogenase reaction

Chin, J.K. and Klinman, J.P. (2000). Probes of a role for remote binding interactions on hydrogen tunneling in the horse liver alcohol dehydrogenase reaction. Biochemistry 39, 1278-1284... 

B. V. PiAPP, J. P. Klinman, Unmasking of hydrogen tunneling in the horse liver alcohol dehydrogenase reaction by site-directed mutagenesis. Biochemistry 32, 5503-5507 (1993). 

Once intrinsic isotope effects are determined, one is in a position to deduce transition state stmcture, just as the physical organic chemist does for nonen-zymic reactions. Unfortunately, in many cases workers have assumed, rather than proved, that commitments are zero and intrinsic isotope effects were being looked at. Transition state structures have been investigated in the formate and liver alcohol dehydrogenase reactions as the redox potential of the nucleotide substrate was changed (103, 118). Primary deuterium and C, secondary deuterium, and for formate dehydrogenase 0 isotope effects were determined. In both cases the transition states appeared to be late with NAD and to become earlier as the redox potential of the nucleotide became more positive. So far the conclusions from such studies have been qualitative in nature, and there is room for much more work on these systems. 

Damgaard SE (1981) Primary deuterium and tritium isotope effects upon V/K in the liver alcohol dehydrogenase reaction with ethanol. Biochemistry 20 5662-5669... 

San Pietro A, Kaplan NO, Colowick SP (1955) Pyridine nucleotide transhydrogenase VI. Mechanism and stereospecificity of the reaction in pseudomonas fluorescens. J Biol Chem 212 941-952 Schmidt J, Chen J, De Traglia M, Minkel D McFarland JT (1979) Solvent deuterium isotope effect on the liver alcohol dehydrogenase reaction. J Am Chem Soc 101 3634-3640 Schowen RL (1978) Catalytic power and transition-state stabilization. In Candour RD, Schowen RL (ed) Transition states of biological... 

Figure 8.27 Reduction of aldehyde in SCCO2 by an isolated enzyme, horse liver alcohol dehydrogenase (HLADH) [20c] (a) Reaction scheme (b) fluorinated coenzyme soluble in CO2 and (c) effect of coenzyme on the reaction.

Several approaches have been undertaken to construct redox active polymermodified electrodes containing such rhodium complexes as mediators. Beley [70] and Cosnier [71] used the electropolymerization of pyrrole-linked rhodium complexes for their fixation at the electrode surface. An effective system for the formation of 1,4-NADH from NAD+ applied a poly-Rh(terpy-py)2 + (terpy = terpyridine py = pyrrole) modified reticulated vitreous carbon electrode [70]. In the presence of liver alcohol dehydrogenase as production enzyme, cyclohexanone was transformed to cyclohexanol with a turnover number of 113 in 31 h. However, the current efficiency was rather small. The films which are obtained by electropolymerization of the pyrrole-linked rhodium complexes do not swell. Therefore, the reaction between the substrate, for example NAD+, and the reduced redox catalyst mostly takes place at the film/solution interface. To obtain a water-swellable film, which allows the easy penetration of the substrate into the film and thus renders the reaction layer larger, we used a different approach. Water-soluble copolymers of substituted vinylbipyridine rhodium complexes with N-vinylpyrrolidone, like 11 and 12, were synthesized chemically and then fixed to the surface of a graphite electrode by /-irradiation. The polymer films obtained swell very well in aqueous... 

Yeast alcohol dehydrogenase (YADH), catalysis of reduction by NADH of acetone formate dehydrogenase (FDH), oxidation by NAD of formate horse-liver alcohol dehydrogenase (HLAD), catalysis of reduction by NADH of cyclohexanone With label in NADH, the secondary KIE is 1.38 for reduction of acetone (YADH) with label in NAD, the secondary KIE is 1.22 for oxidation of formate (FDH) with label in NADH, the secondary KIE is 1.50 for reduction of cyclohexanone (HLAD). The exalted secondary isotope effects were suggested to originate in reaction-coordinate motion of the secondary center. 

In the following year, Cleland and his coworkers reported further and more emphatic examples of the phenomenon of exaltation of the a-secondary isotope effects in enzymic hydride-transfer reactions. The cases shown in Table 1 for their studies of yeast alcohol dehydrogenase and horse-liver alcohol dehydrogenase would have been expected on traditional grounds to show kinetic isotope effects between 1.00 and 1.13 but in fact values of 1.38 and 1.50 were found. Even more impressively, the oxidation of formate by NAD was expected to exhibit an isotope effect between 1.00 and 1/1.13 = 0.89 - an inverse isotope effect because NAD" was being converted to NADH. The observed value was 1.22, normal rather than inverse. Again the model of coupled motion, with a citation to Kurz and Frieden, was invoked to interpret the findings. 

Cook, P.F., Oppenheimer, N.J. and Cleland, W.W. (1981). Secondary deuterium and nitrogen-15 isotope effects in enzyme-catalyzed reactions. Chemical mechanism of liver alcohol dehydrogenase. Biochemistry 20, 1817-1825... 

All the enzymes used in the work described above are quite stable at room temperature and can be used in a free form. They can also be used in an immobilized form to improve the stability and to facilitate the recovery. Many immobilization techniques are available today (25). The recent procedure developed by Whitesides et al using water-insoluble, cross-linked poly(aerylamide-acryloxysuccinimide) appears to be very useful and applicable to many enzymes (37). We have found that the non-crosslinked polymer can be used directly for immobilization in the absence of the diamine cross-linking reagent. Reaction of an enzyme with the reactive polymer produces an immobilized enzyme which is soluble in aqueous solutions but insoluble in organic solvents. Many enzymes have been immobilized by this way and the stability of each enzyme is enhanced by a factor of greater than 100. Horse liver alcohol dehydrogenase and FDP aldolase, for example, have been successfully immobilized and showed a marked increase in stability. 

The Theorell-Chance mechanism is an ordered mechanism in which the ternary complex does not accumulate under the reaction conditions, as is found for horse liver alcohol dehydrogenase ... 

These enzymes, which mainly catalyze hydrolytic reactions, have the zinc ions at their active sites. However, Zn ions also appear necessary in some cases for stabilization of the protein structure, e.g. in Cu/Zn SOD, insulin, liver alcohol dehydrogenase and alkaline phosphatases. 

Semisynthetic enzymatic oxidation of peptide alcohols employs equine liver alcohol dehydrogenase. Amino alcohols with nonpolar side chains and Z-Om[CH2OH] worked as effective substrates while polar amino alcohols such as H-Arg[CH2OH] and H-Lys[CH2OH] failed as substrates. To attain complete oxidation, semicarbazide was present in the reaction mixture to immediately trap the aldehyde, and flavin mononucleotide was used to oxidize the NADH to NAD+, which serves to oxidize the alcohol 41] Configurational stability was confirmed by NMR spectroscopy as in the case of Ac-Phe[CH2OH], which was prepared by sodium borohydride reduction of Ac-Phe-H 4 1... 

The use of ester-cleaving enzymes is probably going to be one of the most useful biological-chemical methods in the synthetic laboratory. No example of this type of reaction has hitherto been published in the Organic Syntheses series of procedures. So far, the only biological-chemical Organic Synfheses-procedures are two yeast reductions,4 5 one oxidation with horse-liver-alcohol-dehydrogenase,6 and a disaccharide synthesis catalyzed by emulsin.7 The procedure described here is... 

Figure 3-24. A zinc(ii) complex which acts as a functional model for the hydride transfer reaction which occurs at the active site of the enzyme liver alcohol dehydrogenase.

Kimura, E., Shionoya, M., Hoshino, A., Ikeda, T., Yamada, Y., A model for catalytically active zinc(II) ion in liver alcohol-dehydrogenase - a novel hydride transfer-reaction catalyzed by zinc (II) -macrocyclic polyamine complexes. J. Am. Chem. Soc. 1992,114, 10134-10137. 

Studies on the various zinc-activated dehydrogenases continue apace. The reduction of tra s-4-iViV-dimethylaminocinnamaldehyde (A) by liver alcohol dehydrogenase (LADH) is reported to involve the zinc at the active site of the enzyme acting as a Lewis acid and co-ordinating the substrate via the aldehyde oxygen.235 The kinetics of the reaction show that (A) 4- LADH -f NADH form a stable intermediate at pH 9, the overall reaction sequence being ... 

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