The word protein was first mentioned in a letter sent by the Swedish chemist Jöns Jakob Berzelius to Gerhardus Johannes Mulder on July 10, 1838. He wrote:

The name protein that I propose for the organic oxide of fibrin and albumin, I wanted to derive from the Greek word πρωτειος, because it appears to be the primitive or principal substance of animal nutrition.

In twentieth-century study of proteins, one of the more striking discoveries was that the native and denatured states in many proteins were interconvertible (denatured refers to a protein that is not in its native state and is generally lacking a well-defined secondary structure). That is, by careful control of solution conditions to separate a denatured protein from the denaturing chemical, a denatured protein could be converted to its native form. The question of how proteins arrive at their native state is an important area of biochemistry, called the study of protein folding.

Through genetic engineering, researchers can alter the amino acid sequence and hence the structure, targeting, susceptibility to regulation, and other properties of a protein. The genetic sequences of different proteins may be spliced together to create chimeric proteins that possess properties of both. This form of tinkering represents one of the chief tools used by cell and molecular biologists to understand the workings of cells. Another area of protein research attempts to engineer proteins with entirely new properties or functions, a field known as protein engineering.