The biosynthesis of tuberin from tyrosine and glycine; observations on the stereochemistry associated with the conversion of glycine through methylenetetrahydrofolate into methenyltetrahydrofolate

Abstract

Tuberin (1) is shown to derive from glycine by way of tetrahydrofolate metabolism and from tyrosine. Glycine is incorporated into the N-formyl group of tuberin with (partial) stereospecific retention of the 2-pro-S proton; there is also some non-stereospecific loss of deuterium label from [2-¹³C, 2-²H₂]glycine on incorporation into the C₁ units present in tuberin. [2-¹⁴C]-threo-3-Hydroxytyrosine [as (7)] is only incorporated into tuberin after degradation; exclusive labelling of the two C₁ units was observed. [2-³H]Octopamine [as (6)] is a poor precursor for tuberin.