Hello,

I came across this paper: Production of isotopically enriched high molecular weight hyaluronic acid and characterization by solid-state NMR, available on researchgate in preprint form. They state that they produced isotopic hyaluronic acid from D-Glucose U13-C6 (essentially, all carbon atoms labeled with 13C). When they analyzed the isotopic hyaluronic acid with MS, they found that 22% of the hyaluronic acid produced had 1 unlabeled carbon and 16 % had 2 unlabeled carbons, which presumably forms from unlabeled acetate, which is formed from other carbon sources present in the medium which are not 13C labeled. But I have no clue how a 1 carbon unlabeled HA could form. I thought maybe its from gluconeogenesis, but from what I understand, the HCO3- that gets added to pyruvate in the first step immidiatelly leaves in the next step as CO2.

Does anyone have an idea how could hyaluronic acid have formed with 1 unlabeled carbon?