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Serum albumin

Blood proteins such as hemoglobin, alpha-1-antitrypsin (AAT), fibrinogen, human serum albumin, thrombin, antithrombin III, antibodies, blood coagulation factors (e.g. Factors V-XIII), and others are known to have therapeutic potential for a number of human conditions. The most abundant protein component in circulating blood of mammalian species is serum albumin, which is normally present at a concentration of approximately 3 to 4.5 grams per 100 milliters of whole blood. Albumin is a transport protein molecule that carries out many functions in mammalian serum biology, notably that of a carrier of hormones and other soluble ligands from site to site, and other activities that contribute largely to general mammalian biochemistry. Serum albumin is a blood protein of approximately 70,000 daltons which provides several important functions in the circulatory system. For instance, it functions as a transporter of a variety of organic molecules found in the blood, as the main transporter of various metabolites such as fatty acids and bilirubin through the blood, and, owing to its abundance, as an osmotic regulator of the circulating blood. The serum albumins belong to a multigene family of proteins that includes alpha-fetoprotein and human group-specific component, also known as vitamin-D binding protein. The members of this multigene family are typically comprised of relatively large multi-domain proteins, and the serum albumins are the major soluble proteins of the circulatory system and contribute to many vital physiological processes. The serum albumin has various kinds of functions including an antibacterial activity, an antioxidative effect, an inflammation inhibitory effect, an in vivo substance transporting action, and an enzymatic activity. Human serum albumin (HSA) is a main protein found in the serum of an adult, is produced in the liver, and has a function as a carrier for transporting various serum molecules. A major function of serum albumin is to maintain a natural osmotic pressure of plasma and to transport sparingly soluble substances throughout the body. HSA has an outstanding ability to bind and transport a wide spectrum of ligands throughout the circulatory system including the long-chain fatty acids which are otherwise insoluble in circulating plasma. Serum albumin also functions as a carrier of endogenous and exogenous molecules, and for many years it has been thought to be devoid of any enzymatic function. The albumin has an important role in maintaining at a normal level a plasma colloid osmotic pressure caused by a solute (colloid) which cannot pass through pores of a capillary vessel, to maintain a liquid content in blood. Therefore, the albumin has been used for treatment of various conditions associated with a liquid loss from a blood vessel, including administration for surgery, shock, burn, and a low protein blood disease that causes an edema. Human serum albumin has been used clinically in protein replacement therapy and as a plasma expander for patients that have experienced blood loss, e.g., resulting from surgery, burns, trauma, or shock.

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