LECTURE 4- B, oxidation of lipids Flashcards
(29 cards)
What did Franz knoop discover and when ?
1904
labelled fatty acid groups with phenyl groups
- Fed dogs fatty acids with marker (phenyl at the methyl end)
- Purpose of phenyl- to block degradation
- examined excretion products
- some fatty acids have odd numbers and c
- some had even
Odd number chain lengths formed- experiment Franz Knoop ? Why was this occurring?
Benzoate- odd (no ch2 left between phenyl and COOH group)
phenyl acetate- even (ch2 left between phenyl and COOH group)
carbons were removed as pairs (from b carbon)
oxidation occurs where?
b CARBON
which is c3 away from carboxyl group (including)
3 steps to oxidation? - general names given
1) Activation
2) Transport of the activated molecule
3) Oxidation
Activation step: first step
fatty acid becomes attached to CoA> acyl CoA
Where does activation occur?
Outside the mitochondria.
Enzyme which controls the activation step?
Acyl- CoA synthesase
Overall reaction for activation step?
type of reaction that is occurring?
RCOO- +CoA + ATP > ACYL- CoA +AMP +PPi
freely reversible
How is the activation step driven in the forward direction?
Pyrophosphatase which forms 2Pi from PPi
technically removing products from the right side, le chateliers principle.
Why is ‘activation’ a common first step of metabolic pathways?
ensure the -ve delta g of subsequent reactions
The transport step was discovered by?
Lehninger-1948
Transport of the product of activation step, to where?
mitocondira
Use of carnitine ?
intermediate
Carnitine (in place of a OH present in the molecule) attaches to acyl group and CoA-sh is released
most common carbon length fatty acid? Therefore requires how many oxidation cycles?
16 carbons long
7 cycles
Four steps in which are required in the 3rd (oxidation step) of beta oxidation
1) Oxidation
2) Hydration
3) Oxidation
4) Thiolytic cleavage
In the first step of oxidation?
- Reatant
- Product
in general and referring the palmitate example
- Palmitoyl CoA
- Enoyl-CoA
general
- oil CoA
- Enoyl CoA
In the first step of oxidation?
- Reaction type and occurrence
Oxidation
A double bond is formed between carbon 3,2 (from carboxyl end)
In the first step of oxidation?
- enzyme
- cofactor
- Acyl- CoA DH
- FAD
Type of reaction for step two of the oxidation step
Hydration across the bond between 2,3
Enzyme which is used for the second step during oxidation
Enoyl-CoA hydratase
Starting molecule and end molecule of the second step of oxidation?
Enoyl-CoA
B- hydroxy-acyl-CoA
Type of reaction for step three of oxidation?
Oxidation
Enzyme and cofactor which controls the 3rd step of oxidation ?
B-hydroxyl-acyl-CoA DH
cofactor:NAD+
What happens in terms of the change of structure in the 3rd step of oxidation?
Beta carbon is oxidised forming a c=0 bond at c3 (from coo- end)
