Plasma Proteins and Albumin PDF - Overview and Functions

Overview of plasma proteins and enzymes Albumin- 60 % (maintains oncotic pressure) Globulin-35% ( Consists of antibodies and transport proteins) Fibrinogen-4% ( Blood clotting ) Others less than-1% (Various roles)​ ​ Building blocks of proteins Amino acids -​ Made of amino group, Hydrogen, Carbo...

Overview of plasma proteins and enzymes Albumin- 60 % (maintains oncotic pressure) Globulin-35% ( Consists of antibodies and transport proteins) Fibrinogen-4% ( Blood clotting ) Others less than-1% (Various roles)​ ​ Building blocks of proteins Amino acids -​ Made of amino group, Hydrogen, Carboxylic acid group, alpha carbon and a R-group -​ Building blocks of proteins -​ L-forms are naturally found in humans Classification of amino acids -​ There are 20 amino acids classified by polarity and charge properties -​ Hydrophobic amino acids→ have non polar R-groups and usually found at interior of proteins or at the surface where they interact with lipids -​ Hydrophilic amino → R groups form hydrogen bonds and are found n the surface where they interact with water Proteins -​ Polypeptide chain: amino acids join to each other via peptide bonds to form polypeptide chains (primary structure) -​ Structural levels in proteins -​ Primary: sequence of amino acids -​ Secondary: Coiled a-helix and beta-pleated sheets or a triple helix formed by hydrogen bonding between peptide bonds along the chain -​ Tertiary: a folding of protein into compact, three dimensional shape stabilized by interactions between side R-groups of amino acids -​ Quaternary: A combination of 2 or more protein subunits to form a larger, biologically active protein -​ Diagrams of protein structure levels  -​ Proteins Digestion and Metabolism -​ At the stomach, HCL and pepsin is released to digest protein in food into peptides -​ At the intestines, HCO3-, Trypsinogen, Chymotrypsinogen, Proteolastase, Procarboxypeptidase A and B released by both the pancreas and the small intestine -​ Aminopeptidases released in the blood break down the peptides further into di and tripeptides + amino acids -​ These then pass through the epithelial cells lining the intestine -​ From there, the absorbed amino acids are delivered to various parts of the cells and can be re assembled into proteins in the liver -​ The R- groups can be used in making carbohydrates or lipid storage -​ In the fasting state, amino acids are metabolized for energy or contributing towards a much-needed glucose source (gluconeogenesis) -​ Catabolism of amino group expelled from the body in the form of urea -​ The nitrogen in the amino acid is excreted in the form of urea in the urine -​ The amount of nitrogen ingested is the same as the nitrogen excreted -​ This phenomenon is known as nitrogen balance Plasma proteins Plasma proteins -​ Proteins are present in all body fluids -​ Plasma proteins are most frequently used for diagnostics purposes -​ Intracellular enzymes detected in plasma provides a sensitive,non-specific indicator of tissue damage Function of plasma proteins -​ Transportation -​ Transferrin, haptoglobin, lipoproteins haemoglobin -​ Enzymatic  -​ Intracellular enzymes such as AST, ALT, LDH, ALP -​ Immunity -​ Immunoglobulins -​ Maintaining oncotic pressure -​ Mainly proteins, specifically albumin -​ Clotting factors -​ Coagulation factors and complement proteins -​ Inflammation -​ Examples are acute phase reaction proteins such as CRP, antitrypsin etc Total protein levels CSF: 6 mg/L) suggests renal impairment and increased tumor activity. 4. Hyponatraemia ​ Paraproteinaemia can replace plasma water with protein, leading to low sodium levels (hyponatraemia). 5. Anaemia & Blood Cell Suppression ​ Plasma cell overgrowth in the bone marrow interferes with the production of RBCs, WBCs, and platelets, causing anaemia. 6. Bone Lesions & Fractures ​ Bone pain, destruction, and fractures mainly affect lumbar vertebrae, ribs, and pelvis. ​ If spinal nerves are affected, it may lead to numbness or paralysis. Types of Proteinuria 1. Normal Renal Protein Threshold  ​ Normal limit: ≤150 mg/day of protein in urine. ​ Abnormal proteinuria occurs when proteins exceed this threshold due to kidney dysfunction. 2. Proteinuria in Systemic Conditions ​ Multiple myeloma → Bence-Jones proteins (low molecular weight). ​ Intravascular hemolysis → Hemoglobin in urine. ​ Low molecular weight proteins (