Download - Oxidation and Reduction
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Lecture 4 Slides
Oxidation and
Reductionas it pertains to biochemistry
Read The Slow Burnplease read
fig 13-22
fig 13-22
fig 13-23
reduction potentialcan be measured
testcell
ref.cell
Redox reactions as pairs of half-reactions
Fe2+ + Cu2+Fe3+ + Cu+
The half-reactions:
Fe3+ + e- Fe2+
Cu2+ + e- Cu+ E'o = -.18
E'o = .77
always reductions!rh
Energetics calculated from half-reactions
Fe2++ Cu2+Fe3+ + Cu+
Cu2+ + e-Cu+ E'o =.18
what is E'o for this reaction ?
E'o = (.18 +.77)
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Fe2+ + Cu2+Fe3+ + Cu+
Fe3+ + e- Fe2+ E'o = .77
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DG'o = -nFE'o
one confusing thing: by the convention, positive E means spontaneous reaction… or negative DG.
relationship between free energy and reduction potential
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Energetics calculated from half-reactions
Fe2++ Cu2+Fe3+ + Cu+
Cu2+ + e-Cu+ E'o = .18
what is E'o for this reaction ?
E'o = 0.95
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Fe2+ + Cu2+Fe3+ + Cu+
Fe3+ + e- Fe2+ E'o = .77
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DG'o = -nFE'o
nFE'o
glucose
Fe2+ + Cu2+ Fe3+ + Cu+
familiar from earlier chemistry classes…
BUT WHAT ABOUT SOMETHING LIKE THIS?:
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Oxidation of a "model" sugar molecule: CH2O
glucose
general:
let's make n=1, to aid understanding
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Oxidation of a "model" sugar molecule: CH2O
1) removal of electrons from sugar
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Oxidation of a "model" sugar molecule: CH2O
2) reduction of oxygen
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Oxidation of a "model" sugar molecule: CH2O
3) production of CO2
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TOP
MID
DLE
BO
TTO
MTable of Standard Reduction Potentials
fig 13-24
NAD+ and NADH
The business end of NAD and NADP
this moiety is from the vitamin niacinrh
this moiety is from the vitamin niacinrh
moi·e·ty (moi-t)n.One of two or more parts into which something may be divided, such as the various parts of a vitamin or molecule.
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table 13-8
fig 13-27
FAD and FADH2 (and FMN and FMNH2)
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The business end of FAD or FMN
this moiety is from the vitamin riboflavin
isoalloxazinering
fig 13-9