Post on 15-Jan-2016
description
Krebs cycle
phosphofructokinase *
hexose kinase
aldolase
triose phosphate isomerase
phosphogyceraldehyde dehydrogenase
phosphoglycerate kinase
pyruvate kinase *
Lactate (or ethanol + CO2)
NAD+ NADPH
To TCA cycle
The matrix contains Pyruvate Dehydrogenase, enzymes of Krebs Cycle, and other pathways, e.g., fatty acid oxidation & amino acid metabolism.
The outer membrane contains large VDAC channels, similar to bacterial porin channels, making the outer membrane leaky to ions & small molecules.
matrix
inner membrane
outer membrane
inter- membrane
space
mitochondrion
cristae
Glycolysis occurs in the cytosol of cells.
Pyruvate enters the mitochondrion to be metabolized further.
Mitochondrial Compartments:
It contains various transport catalysts, including a carrier protein that allows pyruvate to enter the matrix.
It is highly convoluted, with infoldings called cristae.
Embedded in the inner membrane are constituents of the respiratory chain and ATP Synthase.
matrix
inner membrane
outer membrane
inter- membrane
space
mitochondrion
cristae The inner membrane is the major permeability barrier of the mitochondrion.
Pyruvate (3 C)
Acetyl Co A (2C)NAD+ NADH +CO2
Oxaloacetate (4C) Citrate (6C)
Ketoglutarate (5C)
NAD+ NADH +CO2
Succinyl CoA (4C)
CoA + NAD+ NADH +CO2
GDP GTP +CoA
Succinate
Fumarate
Malate
FADH2FAD
HOH
NAD+ NADH
Pyruvate Dehydrogenase, catalyzes oxidative decarboxylation of pyruvate, to form acetyl-CoA.
H3C C C O−
O O
C S
O
H3C CoA
HSCoA
NAD+NADH
+CO2
P yruv ateD ehydrogenase
pyruvateacetyl-CoA
Acetyl CoA functions as: input to Krebs Cycle, where the acetate moiety is
further degraded to CO2. donor of acetate for synthesis of fatty acids, ketone
bodies, & cholesterol.
glucose-6-P
Glycolysis
pyruvate fatty acids
acetyl CoA ketone bodies cholesterol
oxaloacetate citrate
Krebs Cycle
3 ATP
3 ATP
3 ATP
2 ATP
3 ATP1 ATP
Pyruvate (3 C)
Acetyl Co A (2C)NAD+ NADH +CO2
Oxaloacetate (4C) Citrate (6C)
Ketoglutarate (5C)
NAD+ NADH +CO2
Succinyl CoA (4C)
CoA + NAD+ NADH +CO2
GDP GTP +CoA
Succinate
Fumarate
Malate
FADH2FAD
HOH
NAD+ NADH
Scorecard:
2 ATP/glucose anaeobic gycolysis
In addition, aerobically we get
~6 ATP from glycolysis NADH
~6 ATP from pyruvate dehydrogenase NADH
~18 ATP from TCA cycle NADH
~4 ATP from TCA cycle FADH
2 ATP from TCA cycle GTP
So: aerobic metabolism ‘classically’ adds ~36 ATP, giving 38 altogether. As I’ll make clear, a bit less than this is made in reality.
Respiration
• Glycolysis and the TCA cycle produce NADH, FADH2 and ATP (via GTP) as primary products, CO2 as a byproduct
• Most of the ATP is made by transfering electrons from NADH and FADH2 to oxygen, forming water
• This is done in the inner membranes of mitochondia and is called respiration
Succinate UQ reductase
2H+
B
AH2
A
C2e-
2e-
2e-
2H+-
Inside (N Side)
Outside (P Side)
Mitchell’s Chemiosmotic Loop