What Are the Main Functions of Blood Serum Proteins?
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Human blood serum contains about 7% protein, with two-thirds in the albumin fraction and the remaining third in the globulin fraction. A large albumin peak, as well as three smaller globulin peaks, alpha-, beta-, and gamma- globulins, are visible on serum electrophoresis. Normal human serum contains about 1.5 percent alpha-, 1.9 percent beta-, and 1.1 percent gamma-globulin, respectively. Each globulin fraction is a complex mixture of proteins, as demonstrated by immuno electrophoresis.
In this method, serum from an animal (for example- a rabbit) injected with human serum is allowed to diffuse into the four protein bands obtained from human serum electrophoresis: albumin, alpha-, beta-, and gamma- globulin. Because the animal has previously been injected with human serum, its blood contains antibodies (substances formed in response to the introduction of a foreign substance into the body) against each of the human serum proteins; each antibody combines with the serum protein ( known as antigen) that caused its formation in the animal.
As a result, approximately 20 regions of insoluble antigen-antibody precipitate form, which appear as white arcs in the electrophoresis medium's transparent gel. Each region is associated with a different human serum protein.
Serum albumin is much less heterogeneous (has fewer distinct proteins) than globulins; in fact, it is one of the few serum proteins that can be obtained in crystalline form. Serum albumin readily combines with many acidic dyes (for example, Congo red and methyl orange); bilirubin, the yellow bile pigment; and fatty acids. It appears to act as a carrier for certain biological substances in living organisms.
Serum albumin, which is present in relatively high concentrations in blood serum, also functions as a protective colloid, a protein that stabilises other proteins. Albumin (molecular weight 68,000) has a single free sulfhydryl (SH) group that forms a disulfide bond with the sulfhydryl group of another serum albumin molecule upon oxidation, resulting in the formation of a dimer. Serum albumin has an isoelectric point of pH 4.7.
What is the Alpha-Globulin Fraction of Blood Serum?
The alpha-globulin fraction of blood serum is a complex mixture of conjugated proteins. The most well-known are a -lipoprotein (a lipid-protein combination) and two mucoproteins (combinations of carbohydrate and protein). One mucoprotein is known as orosomucoid, or 1-acid glycoprotein, while the other is known as haptoglobin because it binds specifically to globin, the protein component of haemoglobin.
Haptoglobin is composed of approximately 20% carbohydrate. In addition to lipoproteins and mucoproteins, the beta-globulin fraction of serum contains two metal-binding proteins, transferrin and ceruloplasmin, which bind iron and copper, respectively. They are the primary carriers of iron and copper in the blood.
What are Serum Proteins?
The total serum protein test determines the amount of protein in the blood. It also assesses the levels of two major protein groups in the blood: albumin and globulin. Albumin is a type of protein. This is primarily produced in the liver. It prevents blood from leaking from blood vessels.
What is Serum Globulin Meaning?
The serum globulin electrophoresis test determines the concentrations of proteins known as globulins in the fluid portion of a blood sample. This fluid is known as serum.
Serum Globulin Low
Renal disease, hepatic dysfunction, celiac disease, inflammatory bowel disease (IBD), and acute hemolytic anaemia can all lead to a drop in globulin levels. This is also an indication that proteins ingested by the digestive system are not being properly broken down or absorbed. A low ratio may indicate autoimmune disorders, impaired kidney function, or liver disease. A high ratio may indicate the presence of certain types of cancer or genetic conditions. The results of a globulin test are not used by themselves.
Serum Creatine Kinase
If your CK-MM enzymes are higher than normal, you may have a muscle injury or disease, such as muscular dystrophy or rhabdomyolysis. If you have higher-than-normal CK-MB enzymes, it could indicate that you have heart muscle inflammation or that you are having or have recently had a heart attack.
Creatine kinase (CK) is an enzyme found in many tissues, including the heart, brain, skeletal muscle, and others. When there is muscle damage, more CK is released into the bloodstream. This test determines the level of creatine kinase in the blood.
Low Serum Albumin
You may be malnourished if your albumin level is low. It could also indicate that you have liver or inflammatory disease. Acute infections, burns, and stress from surgery or a heart attack can all cause elevated albumin levels.
Your body can't keep fluid from leaking out of your blood vessels if you don't have enough albumin. Inadequate albumin levels can also make it difficult to move important substances throughout your body. Some of these substances are required for vital processes that keep your body fluids in balance.
What Happens When Gamma Globulin is High?
Blood cancers, such as multiple myeloma, Waldenström macroglobulinemia, lymphomas, and chronic lymphocytic leukemias, may be associated with increased gamma globulin proteins. Inflammatory disease that is chronic (for example, rheumatoid arthritis) Infection that is not chronic.
FAQs on Proteins of Blood Serum: Structure, Types & Roles
1. What are the major proteins present in blood serum?
The primary proteins found in blood serum are albumin and globulins. Serum is essentially blood plasma that has had the clotting factor, fibrinogen, removed. While albumin is a single type of protein, globulins are a group that is further divided into alpha, beta, and gamma globulins, each with distinct functions.
2. What is albumin and what is its primary function in the blood?
Albumin is the most abundant protein in blood serum, produced by the liver. Its most important function is to maintain the colloidal osmotic pressure of the blood. This pressure is essential for keeping fluid within the blood vessels and preventing it from leaking into surrounding tissues. Additionally, albumin acts as a transport protein, carrying hormones, vitamins, fatty acids, and calcium throughout the body.
3. How are globulins classified and what are their main roles?
Globulins are a major group of serum proteins classified into three main types based on their properties:
- Alpha (α) and Beta (β) globulins: These are primarily transport proteins produced by the liver. They are responsible for carrying substances like lipids, iron (as transferrin), and copper (as ceruloplasmin).
- Gamma (γ) globulins: Also known as immunoglobulins or antibodies, these are crucial for the immune system. They are produced by plasma cells and work to identify and neutralize foreign pathogens like bacteria and viruses.
4. How does blood serum fundamentally differ from blood plasma?
The key difference between blood serum and blood plasma lies in the presence of clotting factors. Blood plasma is the complete liquid component of blood, which contains water, proteins, nutrients, and clotting factors like fibrinogen. To obtain blood serum, blood is allowed to clot, a process that consumes the fibrinogen. The remaining fluid, devoid of fibrinogen and other clotting proteins, is the serum.
5. Why is maintaining osmotic pressure with albumin so important for circulatory health?
Maintaining osmotic pressure is vital for regulating the balance of fluid between the blood and body tissues. Albumin creates this pressure, which effectively draws and holds water inside the capillaries. Without sufficient albumin, this pressure drops, causing fluid to escape from the blood vessels into the interstitial spaces. This leakage can lead to a condition called edema, which is characterized by swelling in the body's tissues.
6. What are the key functional differences between albumin and globulins?
While both are essential serum proteins, their functions are distinct. Albumin primarily acts as a general-purpose regulator of osmotic pressure and a non-specific transporter for many molecules. In contrast, globulins have more specialised roles. Alpha and beta globulins are involved in the specific transport of particular substances, while gamma globulins function as highly specific antibodies in the adaptive immune response. Therefore, albumin is a regulator and general transporter, whereas globulins perform targeted transport and defensive functions.
7. What is C-reactive protein (CRP) and why is it measured in blood tests?
C-reactive protein (CRP) is a substance produced by the liver in response to inflammation anywhere in the body. While normally present in very low amounts, its concentration in the blood serum increases significantly during an inflammatory event, such as an infection or injury. Consequently, a CRP test is used as a non-specific but important marker to detect, monitor, and manage inflammatory conditions.
