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Figure 22-48 Schematic diagram depicting the coordinated control of glycolysis and the citric acid cycle by ATP, ADP, AMP, P i , Ca 2+ , and the [NADH]/[NAD + ] ratio (the vertical arrows indicate increases in this ratio). Page 837. CH 23: Gluconeogenisis and Pentose Phosphate Pathway.

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slide1

Figure 22-48 Schematic diagram depicting the coordinated control of glycolysis and the citric acid cycle by ATP, ADP, AMP, Pi, Ca2+, and the [NADH]/[NAD+] ratio (the vertical arrows indicate increases in this ratio).

Page 837

slide2

CH 23: Gluconeogenisis

and Pentose Phosphate Pathway

Much as I hate to skip stuff in this chapter, we will cover pp 843-850 and 862-870. Please read section 3 on glycoprotein synthesis, pp 852-861.

You should be able to do all the problems…

gluconeogenesis
Gluconeogenesis
  • This route is important when fasting
  • Precursors: lactate, pryuvate, TCA intermediates, most aa’s (except leu,lys)
  • Entry into gluconeogenisis: OAA
  • Note that animals cannot make glucose from AcetylCoA (plants have the glyoxylate cycle)
slide4

Figure 23-1 Pathways

converting lactate,

pyruvate, and citric acid

cycle intermediates

to oxaloacetate.

Page 844

synthesis and degradation are always separated
Synthesis and degradation are always separated
  • The really good news: Mostly glycolytic enzymes involved.
  • What irreversible enzymes of glycolysis must be bypassed for gluconeogenesis????
  • PK, PFK, HK
figure 23 2 conversion of pyruvate to oxaloacetate and then to phosphoenolpyruvate
Figure 23-2 Conversion of pyruvate to oxaloacetate and then to phosphoenolpyruvate.

Prosthetic group=biotin

Page 845

Hi energy intermediate

slide7

Figure 23-3aBiotin and carboxybiotinyl–enzyme. (a) Biotin consists of an imidazoline ring that is cis-fused to a tetrahydrothiophene ring bearing a valerate side chain.

Raw eggs contain avidin—a protein with very high affinity for biotin

Bacteria (Streptomyces) make avidin analogs like streptavidin—where did we see this recently???

http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/chime/biotin/btn-index.html

slide8

Figure 23-3b Biotin and carboxybiotinyl–enzyme. (b) In carboxybiotinyl–enzyme, N1 of the biotin ureidogroup is the carboxylation site.

Another swinging arm between 2 acitive sites of enzyme!

Page 845

figure 23 4 two phase reaction mechanism of pyruvate carboxylase
Figure 23-4 Two-phase reaction mechanism of pyruvate carboxylase.

Phase 1: carboxylation of biotin

figure 23 4 continued two phase reaction mechanism of pyruvate carboxylase
Figure 23-4 (continued) Two-phase reaction mechanism of pyruvate carboxylase.

Phase II: carboxylation of pyruvate

PEP nucleophillically attacks CO2

Page 846

Biotin accepts H+ from pyruvate→PEP

CO2 produced in active site via elimination

pyruvate carboxylase facts
Pyruvate Carboxylase Facts
  • Catalyzes an important anaplerotic reaction that increases TCA activity
  • Acetyl-CoA allosterically activates PC*
  • *If TCA is inhibited by hi ATP/NADH, OAA →gluconeogenesis
slide12

Figure 23-5 The PEPCK

mechanism. GTP driven decarboxylation of OAA →PEP

slide13

Figure 23-6

Transport of

PEP and OAA from the

mitochondria

to the cytosol.

2 different routes—either via malate or asp

Malate shuttle also moves NADH (required in cytosol for gluconeo-genesis

Page 847

cells second energy currency nadph
Cells’ second energy currency: NADPH!
  • NADPH is required for reductive biosynthesis
    • FA’s
    • Steroids
    • Photosynthesis
    • Etc.
  • NADPH is generated by oxidation of G6P
    • Pentose phosphate pathway (PPP) = hexose monophosphate shunt= phosphogluconate pathway
    • 3 G6P + 6 NADP+ + 3 H2O →6 NADPH + 6 H+ + 3 CO2 + 2 F6P = GA3P
  • Pathway divided into 3 phases
    • Oxidative Reactions
      • Produces Ribulose-5-P
    • Isomerization/Epimerization Reactions
      • Produces Ribose-5-P and Xyulose-5-P
    • Transaldolase and Transketolase Reactions
      • 3 Ru5P ↔r5P + 2 Xu5P

Most cells maintain their [NAD+]/[NADPH] near 1000!!!

slide21

Figure 23-28 Ribulose-

5-phosphate isomerase

and ribulose-

5-phosphate

epimerase.

Page 865

figure 23 31 summary of carbon skeleton rearrangements in the pentose phosphate pathway
Figure 23-31 Summary of carbon skeleton rearrangements in the pentose phosphate pathway.

Page 867

slide26

CH 23: Gluconeogenisis

and Pentose Phosphate Pathway

slide27

Figure 23-1 Pathways

converting lactate,

pyruvate, and citric acid

cycle intermediates

to oxaloacetate.

Page 844

slide29

Figure 23-3a Biotin and carboxybiotinyl–enzyme. (a) Biotin consists of an imidazoline ring that is cis-fused to a tetrahydrothiophene ring bearing a valerate side chain.

slide30
Figure 23-3b Biotin and carboxybiotinyl–enzyme. (b) In carboxybiotinyl–enzyme, N1 of the biotin ureido group is the carboxylation site.

Page 845

figure 23 4 continued two phase reaction mechanism of pyruvate carboxylase phase ii
Figure 23-4 (continued) Two-phase reaction mechanism of pyruvate carboxylase. Phase II

Page 846

slide33

Page 847

Figure 23-5 The PEPCK

mechanism.

slide34

Figure 23-6

Transport of

PEP and OAA

from the

mitochondrion

to the cytosol.

Page 847

slide40

Figure 23-28 Ribulose-

5-phosphate isomerase

and ribulose-

5-phosphate

epimerase.

Page 865

figure 23 31 summary of carbon skeleton rearrangements in the pentose phosphate pathway1
Figure 23-31 Summary of carbon skeleton rearrangements in the pentose phosphate pathway.

Page 867

figure 24 1 chloroplast from corn
Figure 24-1 Chloroplast from corn.

Page 872

Photosynthesis!!! Ch 24

slide48
Figure 24-4 Energy diagram indicating the electronic states of chlorophyll and their most important modes of inter-conversion.

Page 875

slide50

Figure 24-7a Flow of energy through a photosynthetic antenna complex. (a) The excitation resulting from photon absorption randomlymigrates by exciton transfer.

Page 877

slide51
Figure 24-7b Flow of energy through a photosynthetic antenna complex. (b) The excitation is trapped by the RC chlorophyll.

Page 877

figure 24 9 model of the light absorbing antenna system of purple photosynthetic bacteria
Figure 24-9 Model of the light-absorbing antenna system of purple photosynthetic bacteria.

Page 878

slide53
Figure 24-13a Photosynthetic electron-transport system of purple photosynthetic bacteria. (a) A schematic diagram.

Page 883

slide54
Figure 24-13b The approximate standard reduction potentials of the photosynthetic electron-transport system’s various components.

Page 883

slide55

Page 885

Figure 24-15 The Z-scheme

for photosynthesis in plants

and cyanobacteria.

slide56
Figure 24-17 Schematic representation of the thylakoid membrane showing the components of its electron-transport chain.

Page 886

table 24 1 standard and physiological free energy changes for the reactions of the calvin cycle
Table 24-1 Standard and Physiological Free Energy Changes for the Reactions of the Calvin Cycle.

Page 901

slide63
Figure 24-33a X-Ray structure of tobacco RuBP carboxylase. (a) The quaternary structure of the L8S8 protein.

Page 899

slide64

Page 900

Figure 24-34 Probable

reaction mechanism of

the carboxylation

reaction catalyzed by RuBP carboxylase.

figure 24 36 probable mechanism of the oxygenase reaction catalyzed by rubp carboxylase oxygenase
Figure 24-36 Probable mechanism of the oxygenase reaction catalyzed by RuBP carboxylase–oxygenase.

Page 902

ps song http www csulb edu cohlberg songs photosynthesis mp3
PS SONGhttp://www.csulb.edu/~cohlberg/Songs/photosynthesis.mp3