Chapter 16, Problem 14P

Interpretation Introduction

(a) Interpretation:

The compound(s) which become labeled during the reaction and the compounds in which ${}^{14}\text{C}$ will accumulate as a result of the reaction should be identified when ${\text{H}}^{14}{\text{CO}}_3^{-}$ is supplied.

Concept introduction:

The first step in fatty acid synthesis is carboxylation dependent on ATP of acetyl-CoA to malonyl-CoA. The next steps in reaction are formation of Malonyl-ACP and acetyl-ACP.

Biosynthesis of fatty acid requires seven cycles of ${\text{C}}_2$ elongation followed by final step of hydrolysis thus forming palmitate. There are several enzymes and cofactors involved in these reaction steps. The earlier researches showed that long chain fatty acids could be synthesized using soluble extracts of pigeon liver.

Interpretation Introduction

(b) Interpretation:

The role of citrate in the reaction of the conversion of acetyl-CoA to palmitate and CoASH if supplied with ${\text{Mg}}^{2+}$, NADPH, ATP, ${\text{HCO}}_3^{-}$ and citrate.

Concept introduction:

Earlier studies showed activities of acetyl-CoA carboxylase and the first step of fatty acid synthesis can be modified by various metabolites. The malonyl-CoA formation is the first step in fatty acid synthesis and was considered to be the rate limiting step and citrate or isocitrate could affect the activity or rate of reaction.