Question

Need need one of these question for biochemistry

1. Where do the electrons required to introduce a double bond in a fatty acid via FATTY ACID DESATURASE come from?
2. Describe the synthesis steps involved needed to make phosphatidylethanolamine from phosphatidic acid.

Answer 1

"2 electrons come from NADH + H+ and 2 from a single bond in the fatty acid chain".

Longer chain fatty acids are formed by elongation reactions which are catalyzed by the enzymes on the cytosolic face of the ER membrane. Two-carbon units are added sequentially by these reactions to the carboxyl ends of both unsaturated and saturated fatty acyl CoA substrates. Unsaturated fatty acids are characterized by presence of double bonds.

ER system introduces double bonds into long-chain acyl CoAs and employs molecular oxygen and NADH.This reaction requires a complex of three enzymes: NADH-cytochrome b5 reductase, cytochrome b5, and a desaturase. Electrons are transferred from NADH to the FAD of NADH-cytochrome b5 reductase.The heme iron atom of cyt-b5 is then reduced to the Fe^​​​2+ state. The non-heme iron of the desaturase is converted to the Fe^{​​​​​2+}, which then helps it to interact with O_{​​​​​​2} and saturated fatty acyl CoA. A double bond is formed with the release of two molecules of H2O. Two electrons are donated from NADH and two from the single bond of the fatty acyl substrate.