Abstract
Enzymes or proteins are commonly present in oligomeric forms for active biological functions. The formation of protein oligomers, either in nature or by artificial means, can take place via covalent bonding or through weak-bond-network associations. Disulfide bonds are more common in forming covalent protein oligomers. Covalent bound protein oligomers usually have additional elements introduced, while proteins associated through weak-bond-networks usually do not involve any additional bound chemical groups. Proteins are commonly present in stable forms or folds. Oligomerization can occur when stable proteins unfold, creating exposed interfaces for association interactions. One well-known process of weak-bond-network oligomerization is domain swapping (DS). Separating the two touching/interacting domains creates opportunities for similar interactions with different protein molecules, leading to oligomerization. Both disulfide bonding and DS oligomerization can be dynamic (or reversible) at least at low Degree of Polymerizations (DPs). The dynamic nature of the protein oligomerization is important for bioactivity control. The morpheein model and the polymorph model are thus important in quantifying enzyme catalyzed biotransformations. Disulfide bonding and DS can act together to form supramolecules. The formation of supramolecules, such as amyloids, in nature can be benign or harmful. Industrial applications of protein oligomerization exploit the special functions /properties of the resultant supramolecules, such as multiple biofunctions, niche structure, etc..