Question

is the net synthesis of glucose possible from the following compounds?

a) the fatty acid palmitate (16:0), which is degraded to 8 acetyl-CoA

b) glyceraldehyde-3-phosphate

c)leucine, which is degraded to acetoacetate (a compound that is metabolically equivalent to two acetyl-coa groups) and acetyl-coa

d)tryptophan, which is degraded to alanine and aceotoacetate

e) phenylalanine, which is degraded to acetoacetate and fumarate

Answer 1

a. Yes. Palmitate is oxidized to acetyl CoA which can be used to synthesize glucose.
b. Yes. Glyceraldhyde-3-phospahte is an intermediate of glycolysis and gluconeogensis.
c. No. Leucine is a ketogenic amino acid. It can not be utilized for glucose synthesis.
d. Yes. Tryptophan can produce acetyl CoA as the breakdown product. Hence it is a glucogenic amino acid.
e. Yes. Phe and Trp are both glucogenic as well as ketogenic amino acids.

Major gluconeogenic precurssors:
i. Lactate
ii. Glycerol
iii. Glucogenic amino acids
iv. TCA cycle intermediate via conversion to oxaloacetate