In a joint project, groups at Tokai University, Tohoku University and Osaka University have synthesized an insulin analog where one of the disulfide bonds linking the A- and B-chain is replaced by diselenide bonds („seleno-insulin“). X-ray analysis revealed a similar structure, but degradation in vitro by insulin-degrading enzyme IDE (a protease) was much slower (45 % after 8 hrs), suggesting seleno-insulin as a potential long-lasting insulin variety.

https://resou.osaka-u.ac.jp/ja/research/2017/20170411_1