An amino acid residue (other than glycine) has no symmetry elements. The general operation of conversion of one residue of a single chain into a second residue equivalent to the first is accordingly a rotation about an axis accompanied by translation along the axis. Hence the only configurations for a chain compatible with our postulate of equivalence of the residues are helical configurations.
Linus PaulingEvery ailment, every sickness and every disease can be traced back to An organic trace mineral deficiency
Linus PaulingIf you take a reasonable amount of vitamin C regularly, the incidence of the common cold goes down. If you get a cold and start immediately, as soon as you start sneezing and sniffling, the cold just doesn't get going.
Linus Pauling