We take away this H atom, this H atom. We take away two electrons, and we form the following single covalent bond between the two sulfurs. And this is known as a disulfide bond or a disulfide bridge. So some proteins, specifically those proteins that are destined to be in the extracellular environment, these polypeptides, can be cross linked by these disulfide bonds. And once we form the unit of these two cystine molecules, that is known as acsteine. So this spelling and this spelling are not the same.