Old Yellow Enzymes

Riboflavin was first isolated from whey in 1879 by Blyth, and the structure was determined by Kuhn and coworkers in 1933. For the structure determination, this group isolated 30 mg of pure riboflavin from the whites of about 10,000 eggs. The discovery of the actions of riboflavin in biological systems arose from the work of Otto Warburg in Germany and Hugo Theorell in Sweden, both of whom identified yellow substances bound to a yeast enzyme involved in the oxidation of pyridine nucleotides. Theorell showed that riboflavin 5 -phosphate was the source of the yellow color in this old yellow enzyme. By 1938, Warburg had identified FAD, the second common form of riboflavin, as the coenzyme in D-amino acid oxidase, another yellow protein. Riboflavin deficiencies are not at all common. Humans require only about 2 mg per day, and the vitamin is prevalent in many foods. This vitamin... 

Vaz ADN, S Chakraborty, V Massey (1995) Old yellow enzyme aromatization of cyclic enones and the mechanism of a novel dismutation reaction. Biochemistry 34 4246-4256. 

Williams RE, DA Rathbone, NS Scrutton, NC Bruce (2004) Biotransformation of explosives by the Old Yellow Enzyme family of flavoproteins. Appl Environ Microbiol 70 3566-3574. 

An unusual reaction was been observed in the reaction of old yellow enzyme with a,(3-unsat-urated ketones. A dismutation took place under aerobic or anaerobic conditions, with the formation from cyclohex-l-keto-2-ene of the corresponding phenol and cyclohexanone, and an analogous reaction from representative cyclodec-3-keto-4-enes—putatively by hydride-ion transfer (Vaz et al. 1995). Reduction of the double bond in a,p-unsaturated ketones has been observed, and the enone reductases from Saccharomyces cerevisiae have been purified and characterized. They are able to carry out reduction of the C=C bonds in aliphatic aldehydes and ketones, and ring double bonds in cyclohexenones (Wanner and Tressel 1998). Reductions of steroid l,4-diene-3-ones can be mediated by the related old yellow enzyme and pentaerythritol tetranitrate reductase, for example, androsta-A -3,17-dione to androsta-A -3,17-dione (Vaz etal. 1995) and prednisone to pregna-A -17a, 20-diol-3,ll,20-trione (Barna et al. 2001) respectively. 

The enantiomeric reduction of 2-nitro-l-phenylprop-l-ene has been studied in a range of Gram-positive organisms including strains of Rhodococcus rhodochrous (Sakai et al. 1985). The enantiomeric purity of the product depended on the strain used, the length of cultivation, and the maintenance of a low pH that is consistent with the later results of Meah and Massey (2000). It has been shown that an NADPH-linked reduction of a,p-unsaturated nitro compounds may also be accomplished by old yellow enzyme via the flcf-nitro form (Meah and Massey 2000). This is formally analogous to the reduction and dismutation of cyclic enones by the same enzyme (Vaz et al. 1995), and the reductive fission of nitrate esters by an enzyme homologous to the old yellow enzyme from Saccharomyces cerevisiae (Snape et al. 1997). 

Meah Y, V Massey (2000) Old yellow enzyme stepwise reduction of nitroolefins and catalysis of acid-nitro tautomerization. Proc Natl Acad Sci USA 97 10733-10738. 

Stuermer, R., Hauer, B., Hall, M. and Faber, K. (2007) Asymmetric bioreduction of activated C C bonds using enoate reductases from the old yellow enzyme family. Current Opinion in Chemical Biology, 11, 203-213. 

Ehrenberg, A., Eriksson, L.E.G., and Hyde, J.S. 1968. Electron-nuclear double resonance from flavin free radicals in NADPH dehydrogenase ( old yellow enzyme ). Biochimica et Biophysica Acta 167 482-484. 

Fitzpatrick, T.B., Amrhein, N. and Macheroux, P., Characterization of YqjM, an old yellow enzyme homolog from Bacillus subtilis involved in the oxidative stress response. J. Biol. Chem., 2003, 278, 19891. 

This enzyme [EC 1.6.99.1] (also known as old yellow enzyme and NADPH diaphorase) catalyzes the reaction of NADPH with an acceptor to produce NADP+ and... 

OCTOPINE DEHYDROGENASE OFFORD PLOT OHM S LAW Old yellow enzyme,... 

Reduction of 3-nitroacrylates 43 by Saccharomyces carlshergensis Old Yellow Enzyme is the key step in the synthesis of optically pure P-2-amino acids (Scheme 2.18). High yields and enantioselectivities of the initially derived nitro-compounds 44 were achieved. The latter can be further chemically elaborated to the corresponding P-amino acids 45 [20]. 

Scheme 2.18 Chemoenzymatic synthesis of P-2-amino acid 45 using Old Yellow Enzyme .

Another approach to preparing enantiomerically pure carboxylic acids and related compounds is via enanhoselective reduction of conjugated double bonds using NAD(P)H-dependent enoate reductases (EREDs EC 1.3.1.X), members of the so-called Old Yellow Enzyme family [44]. EREDs are ubiquitous in nature and their catalytic mechanism is well documented [45]. They contain a catalytic flavin cofactor and a stoichiometric nicotinamide cofactor which must be regenerated (Scheme 6.23). 

A systematic study on enzymatic catalysis has revealed that isolated enzymes, from baker s yeast or old yellow enzyme (OYE) termed nitroalkene reductase, can efficiently catalyze the NADPH-linked reduction of nitroalkenes. Eor the OYE-catalyzed reduction of nitrocyclohexene, a catalytic mechanism was proposed in which the nitrocyclohexene is activated by nitro-oxygen hydrogen bonds to the enzymes His-191 and Asn-194 [167, 168]. Inspired by this study Schreiner et al. 

The attention of biochemists was first attracted to flavins as a result of their color and fluorescence. The study of spectral properties of flavins (Fig. 15-8) has been of importance in understanding these coenzymes. The biochemical role of the flavin coenzymes was first recognized through studies of the "old yellow enzyme"144 145 which was shown by Theorell to contain riboflavin 5 -phosphate. By 1938, FAD was recognized as the coenzyme of a different yellow protein, D-amino acid oxidase of kidney tissue. Like the pyridine nucleotides, the new flavin coenzymes were reduced by dithionite to nearly colorless dihydro forms (Figs. 15-7 and 15-8) revealing the chemical basis for their function as hydrogen carriers. 

Warburg and Christian showed that the color of this old yellow enzyme came from a flavin and proposed that its cyclic reduction and reoxidation played a role in cellular oxidation. When NADP+ was isolated the proposal was extended to encompass a respiratory chain. The two hydrogen carriers NADP+ and flavin would work in sequence to link dehydrogenation of glucose to the iron-containing catalyst that interacted with oxygen. While we still do not know the physiological function of the old yellow enzyme,b the concept of respiratory chain was correct. 

Occlusion zones 29 Octahedral geometry 311 Octopus, intelligence of 24 Oils, composition of 380 Okadaic acid 545 Old yellow enzyme 783 Oleate hydratase 526, 688 Oleic acid 381 Olfactory responses 558 Oligomer(s)... 

The generation of stereogenic centers by asymmetric reduction of carbon-carbon double-bonds is a current topic in chemoenzymatic synthesis. Though enzymes of the old yellow enzyme (OYE) family were identified to perform alkene reduction and were characterized some years ago [133-135], applications of enoate reductases in natural product syntheses are still rare. Thus, potential applications are also shown in this chapter. With an increasing number of new enoate reductases, such as YqjM reductase from B. subtilis, more and more possible targets for biotransformations can be found. 

Brown BJ, Deng Z et al (1998) On the active site of old yellow enzyme. J Biol Chem 273 32753-32762... 

Fox KM, Karplus PA (1994) Old yellow enzyme at 2 A resolution overall structure, ligand binding, and comparison with related flavoproteins. Structure 2 1089-1105... 

Kataoka M, Kotaka A et al (2004) Cloning and overexpression of the old yellow enzyme gene of Candida macedoniensis, and its application to the production of a chiral compound. J Biotechnol 114 1-9... 

Flail M, Stueckler C et al (2008) Asymmetric bioreduction of activated C=C bonds using Zymomonas mobilis NCR enoate reductase and old yellow enzymes OYE 1-3 from yeasts. Eur J Org Chem 2008 1511-1516... 

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