Metabolic Biochemistry Lecture 9 August 19, 2005 Oxidative phosphorylation Other Pathways of Carbohydrate Metabolism Photosynthesis.

Metabolic Biochemistry

Lecture 9August 19, 2005

Oxidative phosphorylationOther Pathways of

Carbohydrate Metabolism

Photosynthesis

Import of

NADH

into mitochondria

LNC 19-27

Example of a shuttle for oxidizing NADH from the cytosol

LNC 19-26

Getting ATP and ADP

in and out of

mitochondria

LNC 19-25

Biological work

for NADH: P/O ratio ~ 2.5for succinate: P/O ratio ~ 1.5

SUBSTRATE LEVEL PHOSPHORYLATION

GAP + Pi + NAD+ NADH + 1,3 bisphosphoglycerate

1,3 bisphosphoglycerate + ADP ATP + 3 phosphoglycerate

1 ATP produced per NAD+ reducedper GAP used upper 3-PG produced

There is a precise stoichiometry

OXIDATIVE PHOSPHORYLATION

NADH + 1/2 O2 + H+ NAD+ + H2O~ 3 ADP + ~ 3 Pi ~ 3ATP

<3 ATP produced per NADH oxidizedper H2O producedper 1/2 O2 consumed

(P/O ratio ~ 2.5)

There is no precise stoichiometry, because protons can find other paths to return to the matrix

When succinate is the substrate, the P/O ratio is ~1.5,

because only two pumps are used (only 6 protons are pumped per succinate)

Regulation of OXPHOS:

Mitochondria contain DNA (~16.5 kb)

mtDNA encodes

2 rRNAs22 tRNAs

13 proteins (in animals)

mtDNA can have mutations causingmitochondrial diseases

GLUCONEOGENESIS

LNC Chapter 14, Section 14.4

PENTOSE PHOSPHATE SHUNT

LNC Chapter 14, Section 14.5

LNC Fig. 14-15

PhosphoenolpyruvatePEP

fructose-1,6 bisphosphate

phosphatase

phosphatase

pyruvate

first bypass

third bypass

second bypass

LNC Fig. 14-16

BIOTIN is a co-factor utilized for

CARBOXYLATION REACTIONS

THIAMINE PYROPHOSPHATE (TPP)

is a co-factor utilized for

DECARBOXYLATION REACTIONS

LNC Fig. 14-18

in muscle

in liver

first bypass

LNC Fig. 14-19

Chapter 15, Section 15.3 (pp.575)

Coordinated Regulation of Glycolysis and Gluconeogenesis

emphasis on regulation of

phosphofructokinase-1 and

fructose 1,6 bisphosphatase

LNC Fig. 14-16

Phosphofructokinase-1

4 identical subunits (two shown)

1 active site per subunit

1 site for allosteric regulator (ADP/ATP)

LNC Fig. 15.18

Phosphofructokinase-1PFK-1

Fructose bis-phosphataseFBPase

LNC Fig. 15-22

LNC Fig. 15-23

THE PENTOSE PHOSPHATE PATHWAYSection 14.5

two significant products: ribose-phosphate

NADPH

End of Lecture 9

August 19, 2005