In 1926, James B. Sumner, an assistant professor at Cornell University, showed that urease is a protein by examining its crystallized form.[4] Sumner's work was the first demonstration that a pure protein can function as an enzyme, and led eventually to the recognition that most enzymes are in fact proteins, and the award of the Nobel prize in chemistry to Sumner in 1946.[5] The structure of urease was first solved by P. A. Karplus in 1995. Urease was the first ever enzyme crystallized