Figure 22-48 Schematic diagram depicting the coordinated control

Report as inappropriate Your report has been received

Shared by: 98Nr75

Tags

Stats

views:: 133
posted:: 4/10/2012
language:: English
pages:: 70

Public Domain

Document Sample

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
Page 837

indicate increases in
this ratio).
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

• 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)
Page 844

Figure 23-1 Pathways
converting lactate,
pyruvate, and citric acid
cycle intermediates
to oxaloacetate.
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.

Prosthetic group=biotin
Page 845

Hi energy intermediate
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.
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
Figure 23-3b Biotin and carboxybiotinyl–
enzyme. (b) In carboxybiotinyl–enzyme, N1 of the
biotin ureido group 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.
Phase 1: carboxylation of biotin
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
CO2 produced in active pyruvate→PEP
site via elimination
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
Figure 23-5 The PEPCK
mechanism. GTP driven
decarboxylation of OAA
→PEP
Figure 23-6
Transport of
PEP and
OAA from
the
mitochondria
to the cytosol.

2 different
routes—
either via
malate or asp

Malate
Page 847

shuttle also
moves
NADH
(required in
cytosol for
gluconeo-
genesis
Glc-6-Phosphatase unique to kidney and liver
They supply other tissues with glc.

Figure 23-7
Pathways of
gluconeogenesis
and glycolysis.
Page 848
Table 23-1 Regulators of
Gluconeogenic Enzyme Activity.
Page 849
Figure 23-9 The Cori cycle.
Page 850
Cells’ second energy currency:
NADPH!
• NADPH is required for reductive biosynthesis
– FA’s
– Steroids
– Photosynthesis Most cells maintain their [NAD+]/[NADPH] near 1000!!!
– 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
Figure 23-25 The pentose phosphate pathway.
Page 863
Figure 23-26 The glucose-6-
phosphate dehydrogenase
reaction.
Page 864
Figure 23-27 The
phosphogluconate
dehydrogenase reaction.
Page 864
Figure 23-28 Ribulose-
5-phosphate isomerase
and ribulose-
5-phosphate
epimerase.
Page 865
Figure 23-29
Mechanism of
transketolase.
Page 865
Figure 23-30
Mechanism of
transaldolase.
Page 866
Figure 23-31 Summary of carbon skeleton
rearrangements in the pentose phosphate
pathway.
Page 867
“Alfonse, Biochemistry makes my head hurt!!”
\
Page 844

Figure 23-1 Pathways
converting lactate,
pyruvate, and citric acid
cycle intermediates
to oxaloacetate.
Figure 23-2 Conversion of
pyruvate to oxaloacetate and
then to phosphoenolpyruvate.
Page 845
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.
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 Two-phase
reaction mechanism of pyruvate
carboxylase.
Page 846
Figure 23-4 (continued) Two-phase
reaction mechanism of pyruvate
carboxylase. Phase II
Page 846
Page 847

Figure 23-5 The PEPCK
mechanism.
Figure 23-6
Page 847

Transport of
PEP and OAA
from the
mitochondrion
to the cytosol.
Figure 23-7
Pathways of
gluconeogenesis
and glycolysis.
Page 848
Table 23-1 Regulators of
Gluconeogenic Enzyme Activity.
Page 849
Figure 23-25 The pentose phosphate pathway.
Page 863
Figure 23-26 The glucose-6-
phosphate dehydrogenase
reaction.
Page 864
Figure 23-27 The
phosphogluconate
dehydrogenase reaction.
Page 864
Figure 23-28 Ribulose-
5-phosphate isomerase
and ribulose-
5-phosphate
epimerase.
Page 865
Figure 23-29
Mechanism of
transketolase.
Page 865
Figure 23-30
Mechanism of
transaldolase.
Page 866
Figure 23-31 Summary of carbon skeleton
rearrangements in the pentose phosphate
pathway.
Page 867
PPP Song
Figure 24-1 Chloroplast from
corn.
Page 872
Figure 24-3 Chlorophyll
structures.
Page 874
Figure 24-3 (continued)
Chlorophyll structures.
Page 874
Figure 24-4
Energy
diagram
indicating the
electronic
states of
chlorophyll
and their most
important
Page 875

modes of inter-
conversion.
Figure 24-5 Absorption
spectra of various
photosynthetic pigments.
Page 875
Figure 24-7a Flow of energy through a
photosynthetic antenna complex. (a) The
excitation resulting from photon absorption
randomly
migrates
by exciton
transfer.
Page 877
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.
Page 878
Figure 24-13a Photosynthetic electron-
transport system of purple photosynthetic
bacteria. (a) A schematic diagram.
Page 883
Figure 24-13b The approximate standard
reduction potentials of the photosynthetic
electron-transport system’s various components.
Page 883
Page 885

Figure 24-15 The Z-scheme
for photosynthesis in plants
and cyanobacteria.
Figure 24-17 Schematic representation of
the thylakoid membrane showing the
components of its electron-transport chain.
Page 886
Figure 24-18 Detailed diagram of the
Z-scheme of photosynthesis.
Page 887
Figure 24-22 Schematic mechanism of O2
generation in chloroplasts.
Page 889
Figure 24-29 Segregation of
PSI and PSII.
Page 894
Figure 24-
31
The Calvin
cycle.
Page 896
Table 24-1 Standard and Physiological Free
Energy Changes for the Reactions of the Calvin
Cycle.
Page 901
Figure 24-32
Algal 3BPG
and RuBP
levels on
removal
of CO2.
Page 898
Figure 24-33a X-Ray structure of
tobacco RuBP carboxylase. (a) The
quaternary structure of the L8S8 protein.
Page 899
Page 900

Figure 24-34 Probable
reaction mechanism of
the carboxylation
reaction catalyzed by RuBP carboxylase.
Figure 24-35
Light-
activation
mechanism of
FBPase and
SBPase.
Page 902
Figure 24-36 Probable mechanism of the
oxygenase reaction catalyzed by RuBP
carboxylase–oxygenase.
Page 902
Figure 24-37
Photorespiration.
Page 903
Figure 24-38 The C4 pathway.
Page 904
PS SONG

http://www.csulb.edu/~cohlberg/So
ngs/photosynthesis.mp3
“Alfonse, Biochemistry makes my head hurt!!”
\