Albumin

PDB 1ao6 EBI

Albumin is a family of globular proteins that are universally found in the blood plasma of mammals and other animals, as well as in plant seeds and egg white (ovalbumin). The most well-known and abundant form of albumin in human blood is serum albumin, which plays a critical role in maintaining the osmotic pressure necessary for proper distribution of body fluids between intravascular compartments and body tissues. Serum albumin also serves as a plasma protein carrier for various substances including hormones, fatty acids, and medications, and is essential for keeping these substances soluble in the blood.

Structure and Function

Albumin is characterized by its high solubility and ability to bind water, ions, and fatty acids. It has a molecular weight of approximately 66.5 kDa and is composed of a single chain of about 585 amino acids. The structure of albumin is what allows it to play a key role in maintaining blood osmotic pressure, which is crucial for the regulation of fluid balance within the body.

In addition to its role in osmotic pressure regulation, albumin has several other important functions. It acts as a carrier molecule for hormones, vitamins, drugs, and other substances; it has antioxidant properties; and it plays a role in buffering pH. Albumin's ability to bind to a wide variety of substances allows it to transport these molecules throughout the bloodstream.

Clinical Significance

The concentration of albumin in the blood is a key indicator of health. Low levels of albumin (hypoalbuminemia) can indicate a variety of health issues, including liver disease, kidney disease, and malnutrition. Hypoalbuminemia can lead to edema (swelling) due to the decrease in osmotic pressure, which allows fluid to leak out of blood vessels into tissues.

Conversely, high levels of albumin (hyperalbuminemia) are less common and are usually seen in cases of dehydration. Measuring albumin levels is a routine part of medical blood tests and can provide valuable information about a person's overall health.

Albumin in Medical Use

Albumin is used medically in a variety of settings. Human serum albumin, derived from donated blood, is used in the treatment of shock, burns, trauma, and other conditions where it is necessary to restore blood volume and maintain blood pressure. It is also used in the development of albumin-based drugs and for drug delivery systems, exploiting its natural carrier properties.

Sources and Production

While human serum albumin is the most commonly known, albumin is also found in other animals, where it may have similar or slightly different functions. Bovine serum albumin (BSA) is another form of albumin widely used in medical and laboratory research due to its stability and availability.

Recombinant albumin, produced through biotechnology using microbial systems, is an alternative to blood-derived albumin. This method addresses concerns related to the supply and safety of blood products, including the risk of transmitting infectious diseases.

Conclusion

Albumin plays a crucial role in the human body, from maintaining fluid balance to transporting a wide range of substances. Its clinical significance as a marker for various diseases and its utility in medical treatments highlight the importance of this protein in health and disease management.