lipid catabolism

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Lecture 12 Slides

part II intro fig4

Anabolism!!!

Gluconeogenesis

anabolic production of glucose

fig 14-16

Carbohydratesa two-lane highway…

what determinesthese specialsteps?

The glycolysis energy landscape

(pyruvate set to 0)

fig 14-17

First bypass

fig 14-17

First bypass, second step PEPCK

The glycolysis energy landscape

(pyruvate set to 0)

Three big steps down… or up

table 14-2

fig 14-17

First bypass

WHICHTISSUEScan do

GLUCONEOGENESIS?

fig 15-20

WHICH TISSUES can do GLUCONEOGENESIS?

1) LIVER

2) KIDNEY

fig 15-20

WHICH TISSUES can do GLUCONEOGENESIS?

1) LIVER

2) KIDNEY

fig 14-16 top

Three big steps on theway up…

fig 15-20

HOW DOES THE LIVER DECIDE WHETHER TO DO

GLUCONEOGENESISor GLYCOLYSIS?

fig 15-20

Two fates for pyruvate regulation by AcCoA abundance

Fructose bisphosphate is at a key position in both cat and ana

fig 15-15

Remember regulation of PFK-1??

pg 581

fig15-16

When glucose is abundant, so is F2,6BP

F2,6BP acceleratesPFK-1

fig 15-16

When glucose is low, so is F2,6BP

F2,6BP inhibitsFBPase

fig 15-16

When glucose is low, so is F2,6BPWhen glucose is abundant, so is F2,6BP

fig 15-17

Separate distinct enzyme activities control Fr2,6BP levels

fig 15-17

…and hormones control these enzymes

fig 15-20

WHAT ARE THECARBON SOURCE(S)

FOR GLUCONEOGENESIS?

fig 15-20

CARBON SOURCE(S) FOR GLUCONEOGENESIS?

1) Lactate

fig 15-20

CARBON SOURCE(S) FOR GLUCONEOGENESIS?

2) Glycerol

lipid menagerie (BLAST from the PAST)

phospholipid

triglyceride

fig 15-20

CARBON SOURCE(S) FOR GLUCONEOGENESIS?

3) Amino acids

table 14-4

CAN WE USEFATTY ACIDS

for GLUCONEOGENESIS?

Can you make glucose from fat using Krebs?

Fat breakdown produces AcCoA (later…)

Krebs cycle converts AcCoA to OAA

OAA can be converted to PEP (PEP-CK)

PEP is the rate-limiting step for synthesis ofglucose (later…)

so, why not?

every time you put an acetate intwo CO2 come out before you get to OAA!

fig 16-13

KREBS! (BLAST from the PAST)

CAN ANY ORGANISM USE

FATTY ACIDS for

GLUCONEOGENESIS?

fancy

The Glyoxylate Cycle

fig 16-20

Glyoxylate Cycle:

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anend runaround carbonloss

isocitratelyase

malate synthase

Plants: the Kings of Glyoxylate…

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Glyoxylate cycle: a cellular biochemist’s view…

fig 16-22 (sort of)

Glyoxylate cycle: a cellular biochemist’s view…

fig 16-22

Glyoxylate cycle: a cellular biochemist’s view…

fig 16-22

Glyoxylate cycle: a cellular biochemist’s view…

fig 16-22

The Biochemical Bottom Line:

fig 16-22

Acetyl-CoA + 3 NAD+ + FAD + GDP + Pi + 2 H2O→

CoA-SH + 3 NADH + 3 H+ + FADH2 + GTP + 2 CO2

Krebs

2 Acetyl-CoA + NAD+ → succinate + NADH + H+

Glyoxylate

Speaking of plants..

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RUBISCO: ribulose

Plants make glucose from… CO2 by photosynthesis

Optical processes (light-dependent reactions) generate ATP and NADPH by use of electron transport and H+ gradients

Biochemical reaction “fixes” CO2 to make 3 carbon precursor…

RUBISCO: ribulose-bis-phosphate carbolxylase

Plants use gluconeogenesis to make glucose from the 3PG made by rubisco…

3PG 1,3bPG

G3P

DHAP

Fr1,6bP etc

ATP and NADPH are employed as the expected substrates

in this process