Question

Please describe metabolic steps that can direct the carbons of palmitate to the uracil ring of uridine monophosphate

Answer 1

This is a very complex question, starting from palmitate to uracil ring. This will occur in 4 steps-

Step 1 – β oxidation of Palmitate to yield acetyl CoA

Fatty acids undergo oxidative removal of successive carbon units in the form of Acetyl CoA, starting from the carboxyl end of fatty acids. Like, palmitic acid contains 16 carbons, which undergo 7 oxidative cycles during β oxidation to yield Acetyl CoA by losing two carbons at a time.

Step 2 – Acetyl CoA to oxaloacetate via TCA cycle

Acetyl CoA enters into the citric acid cycle. A series of enzyme catalyzed reactions help in the formation of oxaloacetate, which serves as precursors for amino acids and glucose.

Step 3 – Aspartate biosynthesis from oxaloacetate

Oxaloacetate undergoes transamination to yield aspartate.

Step 4 – Uracil biosynthesis from aspartate

De novo pyrimidine nucleotide biosynthesis occurs from aspartate. The 6 membered pyrimidine ring is biosynthesised first, followed by its joining to ribose sugar.