METABOLIC BIOCHEMISTRY

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METABOLIC BIOCHEMISTRY Summer 2005 Lecture
6 August 12, 2005
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LNC Chapter 16 The Citric Acid Cycle Krebs
Cycle TCA Cycle
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From G. Perkins, C. Renken, M.E. Martone, S.J.
Young, M. Ellisman, and T. Frey
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Outer membrane
Inner membrane
Matrix
Intermembrane space
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Pyruvate dehydrogenase as seen by
electronmicroscopy
E. coli enzyme Mass gt 4.5x106 24 copies of
trans acetylase (E2) 24 copies of pyruvate
dehydrogenase (E1) 12 copies of dihydro- lipoyl
dehydrogenase
Pyruvate CoASH NAD ? acetyl-CoA
CO2 NADH
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E1
E3
E2
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Coenzyme A
LNC 16.3
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Lipoamide
LNC 16.14
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FAD/FMN FADH2/FMNH2
LNC Fig. 13-18
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Fig. 16.6
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Figure from previous edition of LNC
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TCA CYCLE Krebs cycle Citric acid cycle
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Products from one turn of the Krebs cycle
C2
C6
C4
C6
C4
C5
C4
C4
C4
LNC 16.11
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Citrate Synthase
oxaloacetate yellow acetyl-coA red
open form without substrates
closed from with substrates bound
LNC 16.8
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Iron-sulfur center in aconitase
LNC 16.9
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X
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Stereospecificity of the aconitase reaction with
citrate
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LNC 16.14
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the only membrane- bound enzyme in the TCA cycle
LNC Fig.16.7
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regulatory molecules NADH ATP, ADP Ca2 key
allosteric enzymes the dehydrogenases citrate
synthase
LNC Fig.16.18
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the Krebs cycle is amphibolic
LNC Fig.16.15
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THE GLYOXYLATE CYCLE
LNC Chapter 16, pages 623-626
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C2
C4
C6
C4
C6
C4
C2
C2
LNC Fig.16-20
Note that the figure 16-16 in the 3rd edition has
an error (there is an O instead of an H)
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LNC Fig.16.22
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End of lecture 6 August 12, 2005