The carbonyl group

The aldo-keto reductase (AKR) superfamily comprises proteins that catalyse mainly the reduction of carbonyl groups or carbon–carbon double bonds of a wide variety of substrates including steroids. Such types of reactions have been proposed to occur in the biosynthetic pathway of the cardiac glycosides produced by Digitalis plants. Two cDNAs encoding leaf-specific AKR proteins (DpAR1 and DpAR2) were isolated from a D. purpurea cDNA library using the rat D4-3-ketosteroid 5b-reductase clone.

9p system191 01-06-2013 41 4   Download

The different roles of ubiquinone-10 (UQ10) at the primary and secondary quinone (QAand QB) binding sites ofRho-dobacter sphaeroidesR26 reaction centres are governed by the protein microenvironment. The 4C¼O carbonyl group of QAis unusually strongly hydrogen-bonded, in contrast to QB. This asymmetric binding seems to determine their dif-ferent functions. The asymmetric hydrogen-bonding at QA can be caused intrinsically by distortion of the methoxy groups or extrinsically by binding to specific amino-acid side groups. ...

7p tumor12 20-04-2013 32 2   Download