Question

The β-oxidation of odd-numbered FAs presents a small problem in that once most of the oxidation has occurred, the last component is propionyl-CoA rather than acetyl CoA. This has one more carbon and as such cannot be utilized any further. Outline the events that control the metabolism of this unit in their proper order:

1) Methylmalonyl-CoA epimerase converts S-methylmalonyl-CoA to R-methylmalonyl-CoA.

2) Methylmalonyl-CoA mutase demethylates R-methylmalonyl-CoA to succinyl-CoA.

3) Propionyl-CoA carboxylase catalyzes the addition of CO2 to propionyl-CoA.

4) The odd-carbon FA is metabolized to propionyl-CoA.

A) 4-3-1-2

B)3-1-4-2

C)4-1-3-2

D)2-1-3-4

Answer 1

Answer:

Maybe that your question is incomplete,  in the options following the statement listed none is correct ...

The procedures would have the following order:

1-Propionyl-CoA is converted to Methylmalonyl-CoA thanks to the enzyme Porpionyl-Carboxylase CoA which adheres to a carboxyl modifying the chemical structure (This enzyme depends on ATP, biotin and bicarbonate, to carry out the reaction).

2-Then, Methylmelanolyl-CoA is adhered to a radical, thanks to the enzyme methylmalonyl-CoA racemase, thus generating (R) -methylmalonyl-CoA as a product of the reaction.

3- And finally, (R) -methylmalonyl-CoA is converted to succinyl-CoA, an intermediate of the tricarboxylic acid cycle, by the enzyme methylmalonyl-CoA mutase, which requires cobalamin to catalyze carbon-carbon bond migration.

4-The mechanism of the methylmalonyl-CoA mutase begins with the cleavage of the bond between the 5 'of CH2-5'-deoxyadenosyl and cobalt, which is in its 3 + (III) oxidation state, which produces a 5'-radical. deoxyadenosil and cabalamin in the state of reduced oxidation Co (II)

Explanation:

Propionyl-CoA is important to know that it can come from different biological rations of the organism, such as: beta oxidation (of odd-chain fatty acids), the metabolism of isoleucine and valine and As a product of α-ketobutyric acid, which in turn it is a product of the metabolism of threonine and methionine.

Answer 2

Answer:

A) 4-3-1-2

Explanation:

Order of metabolism is as follows:

Step 1.

The odd-carbon FA is metabolized to propionyl-CoA.

Step 2.

Propionyl-CoA carboxylase catalyzes the addition of CO2 to propionyl-CoA.

Step 3.

Methylmalonyl-CoA epimerase converts S-methylmalonyl-CoA to R-methylmalonyl-CoA.

Step 4.

Methylmalonyl-CoA mutase demethylates R-methylmalonyl-CoA to succinyl-CoA.

propionyl-CoA is used in place of acetyl-CoA as the primer for the biosynthesis of long-chain fatty acids. propionyl-CoA as an odd number of carbon atoms.

Three(3) enzymes are involved in the metabolism.

1. propionyl-Coa carboxylase: this carboxylated the α-carbon of a Propionyl-CoA to produce D-methylmalonyl-CoA.

2. methylmalonyl-CoA epimerase: this enzyme is involved in isomerization reaction.

3. Methylmalonyl-CoA mutase: demethylates R-methylmalonyl-CoA to succinyl-CoA.