Metabolic Biochemistry Lecture 9 August 19, 2005 Oxidative phosphorylation Other Pathways of Carbohydrate Metabolism Photosynthesis
Import of NADH into mitochondria
LNC Example of a shuttle for oxidizing NADH from the cytosol
LNC 19-26
Getting ATP and ADP in and out of mitochondria
LNC Biological work
for NADH: P/O ratio ~ 2.5 for succinate: P/O ratio ~ 1.5
S UBSTRATE LEVEL PHOSPHORYLATION GAP + P i + NAD + NADH + 1,3 bisphosphoglycerate 1,3 bisphosphoglycerate + ADP ATP + 3 phosphoglycerate 1 ATP produced per NAD+ reduced per GAP used up per 3-PG produced There is a precise stoichiometry
OXIDATIVE PHOSPHORYLATION NADH + 1/2 O 2 + H + NAD + + H 2 O ~ 3 ADP + ~ 3 Pi~ 3ATP <3 ATP produced per NADH oxidized per H 2 O produced per 1/2 O 2 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 rRNAs 22 tRNAs 13 proteins (in animals) mtDNA can have mutations causing mitochondrial diseases
GLUCONEOGENESIS LNC Chapter 14, Section 14.4 PENTOSE PHOSPHATE SHUNT LNC Chapter 14, Section 14.5
LNC Fig
Phosphoenolpyruvate PEP fructose-1,6 bisphosphate phosphatase pyruvate first bypass third bypass second bypass LNC Fig
BIOTIN is a co-factor utilized for CARBOXYLATION REACTIONS THIAMINE PYROPHOSPHATE (TPP) is a co-factor utilized for DECARBOXYLATION REACTIONS LNC Fig
in muscle in liver first bypass LNC Fig
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
Phosphofructokinase-1 4 identical subunits (two shown) 1 active site per subunit 1 site for allosteric regulator (ADP/ATP) LNC Fig
Phosphofructokinase-1 PFK-1 Fructose bis-phosphatase FBPase LNC Fig
LNC Fig
THE PENTOSE PHOSPHATE PATHWAY Section 14.5 two significant products:ribose-phosphate NADPH
End of Lecture 9 August 19, 2005