The quartenary structure of a holoenzyme contains four long polypeptide subunits composed of non-polar, polar and charged amino acids. All subunits are properly folded and functional in a water environment. Hydrogen bonds formed with the subunit polypeptides might likely be found:
I. between atoms that comprise the repetitive backbone
II between atoms that comprise the R-groups sidechains in each subunit polypeptides
III between water in the environment and the amino and carboxyl (C-terminal) ends of the polypeptides