Structural biology is concerned with the shape and architecture of large molecules, such as proteins, that carry out most of the activities of living cells. Structural studies explain how proteins carry out specific biological functions. Proteins , which consist of one or more folded amino acid chains, carry out their cellular activities mostly by (a) binding in highly specific ways to other proteins, (b) chemically modifying other molecules by acting as enzymes, and (c ) changing their shapes in response to cellular events.

Protein Folding refers to characteristic folded shapes adopted by proteins. Such shapes are consistent, stable and reproducible within living cells. Since proteins consist of chains of chemically linked amino acids, folding is determined by the amino acid sequence of the chains and by weak attractive and repulsive forces, and by strong chemical bonds, both within particular chains and between chains that bind together. Protein folding refers to the ways that the chains bend and bind together in three dimensions.

Subtilisins are bacterial enzymes that are unusually effective in rapidly degrading other proteins, but are remarkably stable and resistant to degradation themselves.

The three-dimensional structure of subtilisin is depicted here. The red coils indicate secondary corkscrew-like regions known as alpha-helices, while the blue arrows depict structures known as beta-sheets. Such secondary structures contribute to the overall three-dimensional configuration of most proteins.

Pasted from <http://en.wikipedia.org/wiki/Subtilisin

Applications: This remarkable stability makes subtilisins especially useful for a variety of industrial applications. Subtilisins are widely used as cleaning agents in laundry detergents, for example.

The special properties of subtilisins led Dr. Bryan to create a UMBI spinoff company, Potomac Affinity Proteins, which applies the special properties of subtilisin derivatives to a powerful, all-purpose method for industrial protein isolation and purification.