Rafferty Flashcards
what ions are used in oxidation and reduction
hydride ions = H- or H+ + 2e-
what is the structure of NAD
Nicotinamide adenine dinucleotide (phosphate) NAD(P)
dinucleotide 2 ribose rings connected by 2 phosphates
1st ribose is connected to a nicotinamide ring, where the chemistry occurs
2n ribose is connected to an adenine ring
where does hydride transfer occur in NADH
C4 of nicotinamide ring (one opposite to bond with ribose)
what is the difference between NAD+ and NADH
NAD+ is the oxidised form it has 1H on the C4 of the nicotinamide ring - the +ve charge is distributed over the ring
NADH is the reduced form it has 2H on the C4 of the nicotinamide ring - it has lost the charge and the plane is disrupted, N has a lone pair
what is the mechanism of hydride transfer of NADH
the lone pair from the N moves around the ring to the bond to the 2nd H on the C4 of the nicotinamide ring which leaves a hydride ion, attacking a C breaking a carbonyl (C=O)
what is the difference between NADPH and NADP+
an extra P on the 2’ of ribose of adenine
eg. indicates biosynthesis
what is critical to the hydride transfer in NADH
the angle of approach due to stereospecificity
distance ~ 3-3.3A
what is acp
acyl carrier protein
attached via phosphopantetheine arm
covalently linked to Ser residue on ACP
beta-ketoacyl reductase BKR
1st reductive step
Rossman fold
NADPH dependant
tetrameric
what is Rossman fold important for
substrate binding
active site of BKR
conserved lysine (stabilised -ve O on enolate anion) and tyrosine (4 residues apart) near NAD nic ring
active site of ENR and difference between BKR (and why)
conserved lysine and tyrosine are 8 residues apart - the substrate is different
ENR enoyl reductase
final reductive step
NADH dependant
also tetrameric
why is ENR a good drug target
it is in bac. but differnet in euk. so it is a possible anti-biotic
how to draw ENR mechanism
arrow starts from bond between NADH and H (hydride ion)