ALB - Albumin | Elisa - Clia - Antibody - Protein

Background:

Albumin or ALB, is a protein synthesized by the liver and is the most abundant protein in human blood plasma, comprising about 55% to 60% of total plasma protein by weight. It plays several critical roles: Osmotic regulation: Albumin contributes significantly to the oncotic pressure of blood, which helps maintain the balance of fluid distribution between the bloodstream and tissues. This osmotic pressure is crucial for preventing fluid leakage from blood vessels into surrounding tissues. Transportation: Albumin serves as a carrier protein, transporting various substances in the blood, including hormones, fatty acids, bilirubin, calcium, and drugs. By binding to these molecules, albumin helps solubilize them and transport them efficiently throughout the body. Buffering: Albumin acts as a buffer in the blood, helping to maintain pH balance by binding to acidic and basic compounds.Antioxidant: Albumin possesses antioxidant properties and plays a role in scavenging free radicals and protecting cells from oxidative damage.Because of its multiple functions, alterations in albumin levels can indicate various health conditions. Low albumin levels (hypoalbuminemia) can be seen in liver disease, kidney disease, malnutrition, inflammation, and certain chronic conditions. Conversely, high albumin levels (hyperalbuminemia) are less common but can occur in conditions such as dehydration or during recovery from burns.

Protein Structure:

• Molecular Weight: Approximately 66.5 kDa.
• Amino Acid Sequence: Comprises 585 amino acids.
• Domains: Albumin has a heart-shaped structure composed of three homologous domains (I, II, and III), each of which is further divided into two subdomains (A and B). This structure allows albumin to bind to various ligands.
• Binding Sites: Contains multiple binding sites for a wide range of molecules, including fatty acids, hormones, bilirubin, and drugs.

Classification and Subtypes:

• Human Serum Albumin (HSA): The most common form found in human blood plasma.
• Bovine Serum Albumin (BSA): Commonly used in laboratory research and pharmaceutical applications.
• Other Species: Albumins are present in other mammals, with slight variations in structure and function.

Function and Biological Significance:

• Oncotic Pressure: Maintains the oncotic pressure of blood, essential for the proper distribution of body fluids between body tissues and the blood vessels.
• Transport Function: Transports various substances, including hormones, fatty acids, bilirubin, metals, and drugs, facilitating their distribution and metabolism.
• Buffering Capacity: Acts as a pH buffer, helping to maintain acid-base balance.
• Antioxidant Properties: Scavenges free radicals, protecting cells from oxidative damage.
• Nutritional Role: Serves as a source of amino acids during periods of nutrient deprivation.

Interactions:

• Ligands: Binds to a variety of ligands, including fatty acids, bilirubin, calcium, magnesium, and numerous pharmaceuticals, influencing their bioavailability and pharmacokinetics.
• Receptors: Interacts with cellular receptors such as neonatal Fc receptor (FcRn) for albumin recycling and lifespan extension in circulation.

Clinical Issues:

• Hypoalbuminemia: Low levels of albumin in the blood, which can result from liver disease, kidney disease, malnutrition, or acute inflammation. This condition can lead to edema, ascites, and increased risk of infections.
• Hyperalbuminemia: Elevated levels are rare but can occur due to dehydration or certain health conditions.
• Albuminuria: The presence of albumin in urine, often a marker of kidney damage or disease.
• Therapeutic Uses: Albumin is used therapeutically in conditions like burns, shock, and hypoalbuminemia to restore blood volume and protein levels.

Summary:

Albumin, the most abundant plasma protein, is vital for maintaining oncotic pressure, transporting various molecules, and serving as a buffer and antioxidant. Synthesized by the liver, albumin’s multiple binding sites enable it to interact with a wide range of ligands, making it essential for numerous physiological processes. Clinically, albumin levels are crucial indicators of various health conditions.