LECTURE 4- B, oxidation of lipids

Question 1

What did Franz knoop discover and when ?

Answer 1

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

Question 2

Odd number chain lengths formed- experiment Franz Knoop ? Why was this occurring?

Answer 2

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)

Question 3

oxidation occurs where?

Answer 3

b CARBON

which is c3 away from carboxyl group (including)

Question 4

3 steps to oxidation? - general names given

Answer 4

1) Activation
2) Transport of the activated molecule
3) Oxidation

Question 5

Activation step: first step

Answer 5

fatty acid becomes attached to CoA> acyl CoA

Question 6

Where does activation occur?

Answer 6

Outside the mitochondria.

Question 7

Enzyme which controls the activation step?

Answer 7

Acyl- CoA synthesase

Question 8

Overall reaction for activation step?

type of reaction that is occurring?

Answer 8

RCOO- +CoA + ATP > ACYL- CoA +AMP +PPi

freely reversible

Question 9

How is the activation step driven in the forward direction?

Answer 9

Pyrophosphatase which forms 2Pi from PPi

technically removing products from the right side, le chateliers principle.

Question 10

Why is ‘activation’ a common first step of metabolic pathways?

Answer 10

ensure the -ve delta g of subsequent reactions

Question 11

The transport step was discovered by?

Answer 11

Lehninger-1948

Question 12

Transport of the product of activation step, to where?

Answer 12

mitocondira

Question 13

Use of carnitine ?

Answer 13

intermediate

Carnitine (in place of a OH present in the molecule) attaches to acyl group and CoA-sh is released

Question 14

most common carbon length fatty acid? Therefore requires how many oxidation cycles?

Answer 14

16 carbons long

7 cycles

Question 15

Four steps in which are required in the 3rd (oxidation step) of beta oxidation

Answer 15

1) Oxidation
2) Hydration
3) Oxidation
4) Thiolytic cleavage

Question 16

In the first step of oxidation?
- Reatant
- Product
in general and referring the palmitate example

Answer 16

• Palmitoyl CoA
• Enoyl-CoA

general

• oil CoA
• Enoyl CoA

Question 17

In the first step of oxidation?

- Reaction type and occurrence

Answer 17

Oxidation

A double bond is formed between carbon 3,2 (from carboxyl end)

Question 18

In the first step of oxidation?

• enzyme
• cofactor

Answer 18

• Acyl- CoA DH

- FAD

Question 19

Type of reaction for step two of the oxidation step

Answer 19

Hydration across the bond between 2,3

Question 20

Enzyme which is used for the second step during oxidation

Answer 20

Enoyl-CoA hydratase

Question 21

Starting molecule and end molecule of the second step of oxidation?

Answer 21

Enoyl-CoA

B- hydroxy-acyl-CoA

Question 22

Type of reaction for step three of oxidation?

Answer 22

Oxidation

Question 23

Enzyme and cofactor which controls the 3rd step of oxidation ?

Answer 23

B-hydroxyl-acyl-CoA DH

cofactor:NAD+

Question 24

What happens in terms of the change of structure in the 3rd step of oxidation?

Answer 24

Beta carbon is oxidised forming a c=0 bond at c3 (from coo- end)

Question 25

Starting and ending products of the third step of oxidation?

Answer 25

Starting product: L,B,Hydroxyl,-acyl-CoA

Ending product: B.Ketoacyl-coA (now formed a ketone)

Question 26

Name of the process which occurs in step four of oxidation?

Answer 26

Thiolytic cleavage

Question 27

Enzyme involved in the 4th step of oxidation?

Answer 27

Acyl-CoA acetyltransferase (thiolase)

Question 28

Starting and ending production of the 4th step of oxidation?

Answer 28

B-ketoacyl-CoA (in)

acetyl-CoA (2c) + Acyl CoA (depending on how many carbons to start with -2) (out)

Question 29

Substrate required for step 4?

Answer 29

Co-A-sh