What is cysteine ? I have to admit, I didn’t ... What is cysteine ? I have to admit, I didn’t know anything about it. It’s semi-essential amino acid, whose thiol sidechain participates in enzymatic reactions as a nucleophile J It‘ almost like serine, but oxygen atom is replaced with sulphur. Support us if you like it and share this post with your friends. Your benznote #carbonote #mybenznote #benznote #organic #chemistry A post shared by benznote (@benznote) on Sep 6, 2017 at 10:32am PDT