Alpha helix protein structure. Animation showing a polypeptide chain coiling to form an alpha helix, one of the basic secondary structures of a protein. The atoms are colour-coded here: carbon (grey), hydrogen (white), oxygen (red), nitrogen (blue) and sulphur (yellow). Halfway through the animation, the hydrogen bonds (black dotted lines) are shown forming between the carboxyl (C=O) and the amine (NH) group four residues away along the chain. These hydrogen bonds add to the stability of the polypeptide (protein) structure. The final stage of the animation shows the alpha helix (blue) represented schematically with its hydrogen bonds. For a sequence of clips showing the primary, secondary, tertiary and quaternary protein structures, see clips K005/6273, K005/6274, K005/6278 and K005/6276. For the entire sequence with text labels, see clip K005/6277. |