Pyridine nucleotide -dependant

Lynen had studied chemistry in Munich under Wieland his skill as a chemist led to the successful synthesis of a number of fatty acyl CoA derivatives which proved to be substrates in the catabolic pathway. Many of these C=0 or C=C compounds had characteristic UV absorption spectra so that enzyme reactions utilizing them could be followed spectrophotometrically. This technique was also used to identify and monitor the flavoprotein and pyridine nucleotide-dependent steps. Independent evidence for the pathway was provided by Barker, Stadtman and their colleagues using Clostridium kluyveri. Once the outline of the degradation had been proposed the individual steps of the reactions were analyzed very rapidly by Lynen, Green, and Ochoa s groups using in the main acetone-dried powders from mitochondria, which, when extracted with dilute salt solutions, contained all the enzymes of the fatty acid oxidation system. 

The stereospecificity of hydrogen transfer for estradiol-17 and estradiol-17(3 dehydrogenases has been examined by George et a/.84>. These enzymes are both present in chicken liver, and have substrates which differ only in the chirality of their substituents at C—17. Both of these enzymes were shown to use the 4-pro-S or 4B proton of the NADPH. Since the steroid is a bulky substrate, the authors argue that the steric fit between pyridine nucleotide and steroid cannot be as important as the role played by the enzyme in directing the fit. This paper contains an interesting summary of other recent work on the stereospecificity of pyridine nucleotide dependent-steroid dehydrogenases. 

Pyridine nucleotide-dependent dehydrogenases (ed. H. Sund). Berlin—Heidelberg—New York Springer 1970. 

The pharmaceutical and fine chemical industry might use pure hydrogenase or partially purified enzyme preparations in bioconversion applications such as regio and stereoselective hydrogenation of target compounds (van Berkel-Arts et al. 1986). Enzymes are able to catalyse such stereospecific syntheses with ease. However, the cofactors for the NAD-dependent oxidoreductases are expensive. The pyridine nucleotide-dependent hydrogenases such as those from Ralstonia eutropha and hyperthermophilic archaea (Rakhely et al. 1999) make it possible to exploit H2 as a low-cost reductant. The use of inverted micelles in hydrophobic solvents, in which H2 is soluble, has advantages in that the enzymes appear to be stabilized. 

Adams M (1987) Oxido-reductases - pyridine nucleotide-dependent enzymes. In Page MI, Wiliams A (eds) Enzyme mechanisms. The Royal Society of Chemistry, London, p 477... 

Pyridine nucleotide-dependent flavoenzyme catalyzed reactions are known for the external monooxygenase and the disulfide oxidoreductases However, no evidence for the direct participation of the flavin semiquinone as an intermediate in catalysis has been found in these systems. In contrast, flavin semiquinones are necessary intermediates in those pyridine nucleotide-dependent enzymes in which electron transfer from the flavin involves an obligate 1-electron acceptor such as a heme or an iron-sulfur center. Examples of such enzymes include NADPH-cytochrome P4S0 reductase, NADH-cytochrome bs reductase, ferredoxin — NADP reductase, adrenodoxin reductase as well as more complex enzymes such as the mitochondrial NADH dehydrogenase and xanthine dehydrogenase. 

Alcohol dehydrogenase is also obtained from yeast. Yeast alcohol dehydrogenase (YADH) was the first pyridine nucleotide-dependent dehydrogenase to be crystallized by Negelein and Wulff in 1937.1342 YADH is a tetramer of molecular weight 140000-150000. The amount of zinc determined varies,1343 but there are strong indications that the subunits of YADH and LADH have similar structures, including the presence of two zinc atoms. 

C. I. Branddn, E. Zeppezauer, T. Boiwe, C. Sdderlund, B. O. Soderbeg and B. Nordstrom, in Pyridine Nucleotide Dependent Dehydrogenases , ed. H. Sund, Springer-Verlag, Berlin, 1970, p. 133. 

Theorell, H. (1970) in H. Sund (Ed.), Pyridine Nucleotide-Dependent Dehydrogenases, Springer, Berlin, pp. 121-126. 

S. F. Velick tn Pyridine Nucleotide-Dependent Dehydrogenases (H. Sund, ed.), p. 57. Springer-Verlag, Berlin and New York, 1970. 

J. Visser, H. Voetberg, and C. Veeger, in Pyridine Nucleotide-Dependent... 

Jr., G. Zanetti, and S. Ronchi, in Pyridine Nucleotide-Dependent Dehydrogenases ... 

Eisele, B., Wallenfels, K. Pyridine nucleotide-dependent dehydrogenases (ed. H. Sund), p. 91. Berlin - Heidelberg - New York Springer 1970. 

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