Oxidation of L‐[U‐14C]tyrosine with 2.7 molar equivalents of alkaline hexacyanoferrate(III) yielded at least 12 chromatographically mobile oxidation products and a large amount of immobile material. Use of 0.23 molar equivalents of hexacyanoferrate(III) yielded [14C]dityrosine (∼1.3% of added [14C]tyrosine) and [14C]isodityrosine (∼0.6%). A chromatographic method is described for the isolation of these two products from the mixture. A method is also described for the prepration of [3H]isodityrosine from non‐radioactive isodityrosine by catalytic exchange with 3H2. The [3H]isodityrosine formed was essentially stable in 6M HCI at 110°C, indicating that the tritiation occurred at the benzylic groups.
- paper chromatography
- phenolic coupling