authentic protein definition of authentic protein in the Free Online Encyclopedia wholesale mlb jerseys china
protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight. Hundreds of protein molecules have been isolated in pure, homogeneous form; many have been crystallized. All contain carbon, hydrogen, and oxygen, and nearly all contain sulfur as well. Some proteins also incorporate phosphorous, iron, zinc, and copper. Proteins are large molecules with high molecular weights (from about 10,000 for small ones [of 50 amino acids] to more than 1,000,000 for certain forms); they are composed of varying amounts of the same 20 amino acids amino acid, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.Click the link for more information. , which in the intact protein are united through covalent chemical linkages called peptide peptide,organic compound composed of amino acids linked together chemically by peptide bonds. The peptide bond always involves a single covalent link between the (oxygen bearing carbon) of one amino acid and the amino nitrogen of a second amino acid.Click the link for more information. bonds. The amino acids, linked together, form linear unbranched polymeric structures called polypeptide chains; such chains may contain hundreds of amino acid residues; these are arranged in specific order for a given species of protein.Types of ProteinsA protein molecule that consists of but a single polypeptide chain is said to be monomeric; proteins made up of more than one polypeptide chain, as many of the large ones are, are called oligomeric. Based upon chemical composition, proteins are divided into two major classes: simple proteins, which are composed of only amino acids, and conjugated proteins, which are composed of amino acids and additional organic and inorganic groupings, certain of which are called prosthetic groups prosthetic group,non amino acid portions of certain protein molecules. The key part of the prosthetic group may be either organic (such as a vitamin) or inorganic (such as a metal) and is usually required for biological activity, especially when the prosthetic group isClick the link for more information. . Conjugated proteins include glycoproteins glycoprotein, organic compound composed of both a protein and a carbohydrate joined together in covalent chemical linkage. These structures occur in many life forms; they are prevalent and important in mammalian tissues.Click the link for more information. , which contain carbohydrates; lipoproteins lipoprotein, any organic compound that is composed of both protein and the various fatty substances classed as lipids, including fatty acids and steroids such as cholesterol.Click the link for more information. , which contain lipids; and nucleoproteins, which contain nucleic acids nucleic acid,any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.Click the link for more information. .Classified by biological function, proteins include the enzymes enzyme,biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th century chemists.Click the link for more information. , which are responsible for catalyzing the thousands of chemical reactions of the living cell; keratin keratin, any one of a class of fibrous protein molecules that serve as structural units for various living tissues. The keratins are the major protein components of hair, wool, nails, horn, hoofs, and the quills of feathers.Click the link for more information. , elastin, and collagen collagen, any of a group of proteins found in skin, ligaments, tendons, bone and cartilage, and other connective tissue. Cells called fibroblasts form the various fibers in connective tissue in the body.Click the link for more information. , which are important types of structural, or support, proteins; hemoglobin hemoglobin, respiratory protein found in the red blood cells (erythrocytes) of all vertebrates and some invertebrates. A hemoglobin molecule is composed of a protein group, known as globin, and four heme groups, each associated with an iron atom.Click the link for more information. and other gas transport proteins; ovalbumin, casein casein, well defined group of proteins found in milk, constituting about 80% of the proteins in cow's milk, but only 40% in human milk. Casein is a remarkably efficient nutrient, supplying not only essential amino acids, but also some carbohydrates and the inorganic elementsClick the link for more information. , and other nutrient molecules; antibodies antibody,protein produced by the immune system (see immunity) in response to the presence in the body of antigens: foreign proteins or polysaccharides such as bacteria, bacterial toxins, viruses, or other cells or proteins.Click the link for more information. , which are molecules of the immune system (see immunity immunity, china wholesale mlb jerseys