albumin

albumin

(ălbyo͞o`mən) [Lat.,=white of egg], member of a class of water-soluble, heat-coagulating proteins. Albumins are widely distributed in plant and animal tissues, e.g., ovalbumin of egg, myogen of muscle, serum albumin of blood, lactalbumin of milk, legumelin of peas, and leucosin of wheat. Separation of serum albumins from other blood proteins can be carried out by electrophoresis or by fractional precipitation with various salts. Albumins normally constitute about 55% of the plasma proteins. They adhere chemically to various substances in the blood, e.g., amino acids, and thus play a role in their transport. Albumins and other proteins of the blood aid significantly in regulating the distribution of water and maintenance of proper osmotic pressure in the body. Albumins are also used in textile printing, in the fixation of dyes, in sugar refining, and in other important processes.

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Albumin

A type of globular protein that is characterized by its solubility in water and in 50% saturated aqueous ammonium sulfate. Albumins are present in mammalian tissues, bacteria, molds, and plants, and in some foods. Serum albumin, which contains 584 amino acid residues, is the most abundant protein in human serum, and it performs two very important physiological functions. It is responsible for about 80% of the total osmotic regulation in blood, and it transports fatty acids from adipose tissue to muscle. When excessive amounts of albumin are found in the urine upon clinical examination, some form of kidney disease is usually indicated. Another important albumin, ovalbumin, is found in egg white. This protein is about two-thirds the size of serum albumin, and it contains sugar residues in addition to amino acid residues (that is, it is a glycoprotein). See Protein

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

albumin

[‚al′byü·mən]

(biochemistry)

Any of a group of plant and animal proteins which are soluble in water, dilute salt solutions, and 50% saturated ammonium sulfate.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

albumin

, albumen

any of a group of simple water-soluble proteins that are coagulated by heat and are found in blood plasma, egg white, etc.

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005