Hi guys, Welcome to the Advanced Video Search Engine, and you are watching Special cases: Histidine, proline, glycine, cysteine | MCAT | Khan Academy. That video is uploaded by khanacademymedicine at 2013-09-17T09:48:51-07:00. We are promoting this video only for entertainment and educational purpose only. So, I hope you like & enjoy it. [2_IJz1ivopQ]