https://www.estrogen-receptor.com/2017/02/14/the-only-pegylated-variation-of-cvn-that-is-bioactive-is-the-mutant-q62c-in-which-glutamine-62-was-changed-with-a-cysteine-and-the-extra-free-sulfhydryl-was-internet-site-specifically-pegylated-with/