Question

Beta oxidation of fatty acids includes several steps. Following initial coenzyme A activation, these steps include __________.

I.	hydration of double bond
II.	cleavage of carbon-carbon bond and formation of new acyl-CoA
III.	oxidation of β-carbon hydroxyl to keto form
IV.	enoyl formation at the β carbon

What is the correct order of beta oxidation steps?

I, IV, III, II

I, II, III, IV

III, I, IV, II

IV, I, III, II

Answer 1

Correct sequence is IV, I, III, II

* Steps of B-oxidation of fatty acids (R- CH₂ group) Dehydrogenation - H 0 C- C-S-COA ни fatty acyl co A Enzyne - acyl CoA dehydrogenase FAD - FADIL (1) formation at B Carbon (CH16), awa I o=0 - c-s-coA W HYDRATION Enoyl-CoA Hydratase H o © Hydration of double Bord (CHIBR - CA- ca-e-scod ой и DEHYDROGENATION "NADA Enzyme - 3 Hydroxyauyt-cod dehydrogenase NADH THE (11) oxidation of ß-carbon i 8 hydroxyl to keto form (CH16) R - G - C - co ß-keto acyl-CoA 1 THIOLYSIS Enzyme - ß-ketoacyl-CoA thio lase - cleavage of coc bond & formation of new © aryl CA Co-C-S-COA , Acetyl cot & (CHOR-an-e-s-CoA fatty anys COA

In the 1st step of beta oxidation an enzyme acyl Co A dehydrogenase removes hydrogen from beta carbon and makes a double bond between C alpha and C beta. There occurs enoyl formation at the beta carbon.

Then 2nd step is hydration of that double bond to add a hydroxyl group to beta carbon. there occurs hydration of double bond and a hydroxyl group is added to beta carbon.

3rd step is again a dehydrogenation reaction cataylzed by enzyme hydroxyacyl- Co A dehydrodehydrogenase to give product a beta - ketoacyl - Co A. Here occurs the oxidation of beta carbon hydroxyl to keto form.

4th is cleavage of carbon carbon bond and formation of acyl-Co A which is 2 carbon shorter than previous one. This reaction is catalysed by an enzyme called thiolase.

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