Ferredoxin reductase

H)2-D3 is a weak agonist and must be modified by hydroxylation at position Cj for full biologic activity. This is accomplished in mitochondria of the renal proximal convoluted tubule by a three-component monooxygenase reaction that requires NADPFl, Mg, molecular oxygen, and at least three enzymes (1) a flavoprotein, renal ferredoxin reductase (2) an iron sulfur protein, renal ferredoxin and (3) cytochrome P450. This system produces l,25(OH)2-D3, which is the most potent namrally occurring metabolite of vitamin D. 

The degradation of bisphenol-A by Sphingomonas sp. strain AOl is initiated by hydroxylation to intermediates that undergo fission to 4-hydroxyacetophenone and 4-hydroxybenzoate. The components have been purified, and consist of cytochrome P450, ferredoxin reductase, and ferredoxin (Sasaki et al. 2005). 

Ferredoxin rednctases in Pyrococcus furiosus inclnding aldehyde ferredoxin reductase, glyceraldehyde-3-phosphate ferredoxin oxidorednctase, and formaldehyde ferredoxin reductase (Roy et al. 1999). 

The enzymes involved in the degradation of phenanthrene by Nocardioides sp. strain KP7 have been characterized. In this strain, the genes are chromosomal, and phdA and phdB encoding the a- and P-subunits of the dioxygenase, phdC and phdD that encode the ferredoxin, and ferredoxin reductase have been cloned and sequenced (Saito et al. 2000). The order of the genes... 

HSP70 (Ssql) chaperone, J-type (Jacl) cochaperone, and the nucleotide exchange factor Mgel (Dutkiewicz et al. 2003). The process is dependent on the donation of reducing power, which is likely facilitated by [2Fe2S] ferredoxin (Yahlp) and ferredoxin reductase (Arhip). 

Also, by the introduction of the enzyme ferredoxin reductase, a photochemical NADPH regeneration cycle has been established. The NADPH has been utilized in the reduction of ketones to alcohols in the presence of a secondary enzyme, alcohol dehydrogenase. 

Limitations of the system are the low turnover numbers as well as the failure to regenerate NADPH. However, if ferredoxin reductase is used for coenzyme regeneration instead of lipoamide dehydrogenase, this method can also be applied to NADP+-dependent systems [97]. 

There are five classes of flavin-binding structural folds presented in Table 1 that are identified by the prototype protein in which they were first discovered. These are flavodoxin (FDX), ferredoxin reductase (FNR), triosephosphate isomerase (TIM), glutathione reductase (GR) and p-cresol methylhydroxylase (PCMH). The topologies of four of these five domains are shown in Figure 2. There are also four classes of primary acceptor/donor domain folds that are identified by the prototype protein where they were first discovered. They are cytochrome P450BMP (BMP), cytochrome b5 (CYTB5), cytochrome c (CYTC) and the 2Fe-2S plant-type ferredoxin (FDN). 

Rarely termed ferredoxin reductase, PSI is excited maximally by 700 run light, and produces 2 FdREo per 2 PCred oxidised. The electrons are passed from P700 through a series of quinones and iron-sulfur centres to the iron-containing... 

At the time PS 11 absorbs a photon, PS-1 complex also absorbs a photon, resulting in a charge separation to form the oxidized primary electron donor P700 and the reduced primary electron acceptor Aq. The oxidized primary donor P700 is then reduced by an electron from reduced plastocyanin. The electron on the primary acceptor Aq is rapidly transferred step-wise through a series of acceptors consisting of a phylloquinone (0 Q), three iron-sulfur clusters in FeS-X, FeS-A and FeS-B, and finally ferredoxin (Fd) which reduces NADP" to NADPH in a reaction catalyzed by NADP -ferredoxin reductase (FNR). The PS-1 complex is also called the plastocyanin-ferredoxin oxido-reductase. ... 

Fig. 20. Top stereogram of the three-dimensional structure of spinach Fd NADP reductase (FNR) with the p-strands shown as arrows, the o-helices as spirals, and FAD and 2 -phospho-5 -AMP as ball-and-stick models Bottom topological diagram for FNR, with the p-strands shown as arrows, and the a-helices as rectangles. Figure source Karplus and Bruns (1994) Structure-function relations for ferredoxin reductase. J Bioenerg Biomembr 26 92 and Karplus, Daniels and Herriotf (1991) Atomic structure of ferredoxin-NADP reductase Prototype for a structurally novel flavoenzyme family. Science 251 62.

Fig. 22. Stereogram of a plausible orientation for interaction between Fd (top) and Fd-NADP reductase. The Fd molecule is translated upward by about 10 A above FNR for clarity. Figure source Karplus and Bruns (1994) Structure-function relations for ferredoxin reductase. J Bioenerg Biomembr 26 96.

PA Karplus and CM Bruns (1994) Structure-function relations for ferredoxin reductase. J Bioenerg Biomembr 26 89-99... 

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