Improved preparation of semisynthetic PheB1-tritiated insulin

Semisynthetic [PheB1-3H]insulin was prepared. Each intermediate in the synthesis was characterised by HPLC, polyacrylamide gel electrophoresis and end group determination by dansylation. The end product had a specific activity of up to 59 Ci/mmol. Semisynthetic insulin proved indistinguishable from natural insulin in its chemical and immunological properties and was shown to be biologically fully active by in vivo and in vitro assays.