In: Biology
In the citric acid cycle, a double bond is introduced into a four-carbon compound containing the -CH2-CH2- group, producing fumarate. Show a similar reaction that occurs in the Beta-oxidation pathway.
In citric acid cycle, succinate dehydrogenase catalyses the oxidation of succinate into fumarate, in the presence of conenzyme flavin adenine dinucleotiede (FAD). In the reaction of oxidation of succinate to fumarate, two hydrogen atoms are removed from substrate (succinate) by flavin adenine dinucleotide (FAD) and is released as FADH2, thus introduces double bond and forms fumarate.
-OOC-CH2-CH2-COO- + FAD ------SDH-------> -OOC-CH=CH-COO- + FADH2
Likewise in beta oxidationn of fatty acid, oxidation of activated fatty acid, fatty acyl CoA by acyl CoA dehydrogenase results in the formation of alpha-beta- enoyl CoA. This enzyme also requires a coenzyme FAD, two hydrogen atoms are removed from substrate (fatty acyl CoA) by flavin adenine dinucleotide (FAD) and is released as FADH2, thus introduces double bond and forms alpha-beta- enoyl CoA.
R-CH2-CH2-C=O -SCoA + FAD ------Acyl-CoA Dehydrogenase-------> R-CH=CH-C=O-SCoA + FADH2