Protein or the physical region of the protein that participates in chemical catalysis. In solution proteins also undergo variation in structure through thermal vibration and the collision with other molecules. Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes. Fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails. Membrane proteins often serve as receptors or provide channels for polar or charged molecules to pass
The Keg of Nails is a replica of a keg used to ship nails. The exchange is believed to have been initiated by fraternity chapters on the UC and U of L campuses, signifying that the winning players in the game were "tough as nails." The present keg is actually a replacement for the original award, which was misplaced by Louisville, lost during some construction of office facilities. It is adorned with the logos of both schools and the scores of the series games. The rivalry went on hiatus following the 2013 season, as Louisville moved to the Atlantic Coast Conference on July 1,