One well-known example of such a functional nanomachine is myoglobin — an important oxygen-carrying protein in humans that is based on a single polypeptide chain 1. In fact, the 3D structure of ...

THE amphoteric ionic behaviour, one of the characteristics of proteins, has been considered to be due to the presence of the amino- and the carboxyl-groups in the side-chains of the polypeptide chain.

J. Frydman, E. Nimmesgern, K. Ohtsuka, F.U. Hartl, "Folding of nascent polypeptide chains in a high molecular mass assembly with molecular chaperones," Nature, 370:111-7, 1994. (Cited in nearly 50 ...