ETYM Greek protos first: cf. prwteion the first place.
Proteid; organic compound of carbon, hydrogen, oxygen and nitrogen, with other elements, essential to life in food and as part of every living cell.
Complex, biologically important substance composed of amino acids joined by peptide bonds. Proteins are essential to all living organisms. As enzymes they regulate all aspects of metabolism. Structural proteins such as keratin and collagen make up the skin, claws, bones, tendons, and ligaments; muscle proteins produce movement; hemoglobin transports oxygen; and membrane proteins regulate the movement of substances into and out of cells. For humans, protein is an essential part of the diet, and is found in greatest quantity in soy beans and other grain legumes, meat, eggs, and cheese.
Other types of bond, such as sulfur–sulfur bonds, hydrogen bonds, and cation bridges between acid sites, are responsible for creating the protein's characteristic three-dimensional structure, which may be fibrous, globular, or pleated. Protein provides 4 kcal of energy per gram (60 g per day is required).
Any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of long strings of amino acids. + prikaži više