Blood Plasma Proteins Coagulation and Fibrinolysis PDF

2024-10-23 Lim, Yoongho 1 1 four primary types of tissues Epithelial tissue Connective tissue Muscle tissue Nervous tissue 2 2 1 ...

2024-10-23 Lim, Yoongho 1 1 four primary types of tissues Epithelial tissue Connective tissue Muscle tissue Nervous tissue 2 2 1  2024-10-23 Metabolism foods metabolism energy drinks 3 3 SECTION VII Tissue Metabolism Ch 47 The Extracellular Matrix and Connective Tissue Ch 41 Actions of Hormones That Regulate Fuel Metabolism Ch 42 The Biochemistry of Erythrocytes and Other Blood Cells Ch 43 Blood Plasma Proteins, Coagulation, and Fibrinolysis Ch 44 Liver Metabolism Ch 45 Metabolism of Muscle at Rest and during Exercise Ch 46 Metabolism of the Nervous System 4 4 2  2024-10-23 The proteins and cells in the blood form their own tissue system. the stem cell kidney erythropoietin red blood cells anemia 5 5 Red blood cell metabolism to transport oxygen, to regulate oxygen binding to hemoglobin Hematology hematologic system A tear in the wall of a vessel 6 6 3  2024-10-23 Platelets Clots difference between platelet plug and blood clot a platelet plug is a temporary blockage to seal an injury a blood clot is a more permanent seal to the injury until it heals. 7 7 8 8 4  2024-10-23 The blood the plasma. Glucose lipids and steroid hormones The osmotic pressure Plasma proteins 9 9 endothelium-lined blood vessels. hemostasis Blood clots 10 10 5  2024-10-23 hemostasis and thrombosis, a primary hemostatic plug forms at the site of injury consists of aggregated platelets and a fibrin clot Platelets are attached to the subendothelial layer of the vessel through the protein von Willebrand factor Platelets are activated to bind fibrinogen. Fibrinogen binds the platelets The platelet aggregate is covered with layers of fibrin, fibrin is formed from fibrinogen by the proteolytic enzyme thrombin. 11 11 Injury to the endothelium and exposure of tissue factor activate the blood coagulation cascade Regulatory mechanisms and antifibrinolytic mechanisms Impairments in these mechanisms lead to thrombosis. 12 12 6  2024-10-23 Ch43 I. Plasma Proteins Maintain Proper Distribution of Water between Blood and Tissues II. The Plasma Contains Proteins That Aid in Immune Defense III. Plasma Proteins Maintain the Integrity of the Circulatory System 13 13 I. Plasma Proteins Maintain Proper Distribution of Water between Blood and Tissues plasma Extracellular fluid The ionic composition of the interstitial fluid and blood plasma vary due to the Gibbs–Donnan effect 14 14 7  2024-10-23 Gibbs-Donnan effect the unequal distribution of permeant charged ions At Gibbs-Donnan equilibrium, each solution will be electrically neutral The product of diffusible ions will be equal to the product of diffusible ions The electrochemical gradients produces a transmembrane potential difference the Nernst equation an osmotic diffusion gradient 15 15 The mechanisms which maintain the resting membrane potential and the mechanisms of the Gibbs-Donnan effect The Donnan equlibrium is a completely passive process A Donnan equilibrium is an equilibrium 16 16 8  2024-10-23 The plasma proteins function maintaining the proper distribution of water transporting nutrients, metabolites, and hormones maintaining the integrity of the circulation Many diseases alter the amounts of plasma proteins produced and hence their concentration in the blood. These changes can be determined by electrophoresis of plasma proteins (cf, Ch.6 Amino Acids in Proteins) 17 17 I. Plasma Proteins Maintain Proper Distribution of Water between Blood and Tissues A. Body Fluid Maintenance between Tissues and Blood B. The Major Serum Protein, Albumin 18 18 9  2024-10-23 A. Body Fluid Maintenance between Tissues and Blood As the arterial blood enters the capillaries, fluid moves from the intravascular space into the interstitial space due to Starling’s forces. Starling forces hydrostatic pressure and oncotic pressure. Hydrostatic pressure If fluid is in a container, If we picture a column shaped container, 19 19 Oncotic pressure, or colloid osmotic-pressure The hydrostatic pressure in the arteriolar end of the capillaries (~37 mmHg) exceeds the sum of the tissue pressure (~1 mm Hg) and the osmotic pressure of the plasma proteins (~25 mm Hg). Thus, water tends to leave the capillaries and enter extravascular spaces. At the venous end of the capillaries, the hydrostatic pressure falls to approximately 17 mm Hg the osmotic pressure and the tissue pressure remain constant, movement of fluid back from the extravascular spaces and into the blood. most of the force bringing water back from the tissues into the plasma is the osmotic pressure mediated 20 20 10  2024-10-23 A. Body Fluid Maintenance between Tissues and Blood B. The Major Serum Protein, Albumin.1 21 21 albumin osmotic pressure 22 22 11  2024-10-23 Albumin a carrier of free fatty acids, calcium, zinc, steroid hormones, copper, and bilirubin. Many drugs bind to albumin, When a drug binds to albumin, binding will likely lower the effective concentration of that drug may lengthen its lifetime Drug dosimetry may need to be recalculated 23 23 I. Plasma Proteins Maintain Proper Distribution of Water between Blood and Tissues II. The Plasma Contains Proteins That Aid in Immune Defense the immunoglobulins, and the complement proteins immunoglobulins are secreted by a subset of differentiated B lymphocytes bind antigens at binding sites formed (cf. Ch7) 24 24 12  2024-10-23 The complement system becomes activated in either of two ways. interaction with antigen–antibody complexes, interaction of bacterial cell polysaccharides with complement protein C3b. Complement component 3 25 25 Activation of the complement system results in a proteolytic activation cascade resulting in the release of biologically active peptides or polypeptide fragments These peptides mediate the inflammatory response, attract phagocytic cells to the area, initiate degranulation of granulocytes, promote clearance of antigen–antibody complexes. 26 26 13  2024-10-23 I. Plasma Proteins Maintain Proper Distribution of Water between Blood and Tissues II. The Plasma Contains Proteins That Aid in Immune Defense III. Plasma Proteins Maintain the Integrity of the Circulatory System Blood lost from the circulation the subendothelial cell layer is exposed In response to the damage, a barrier is formed at the site of injury. clot formation fibrinolysis 27 27 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation D. Regulation through Feedback Amplification and Inhibition E. Thromboresistance of Vascular Endothelium F. Fibrinolysis G. Regulation of Fibrinolysis 28 28 14  2024-10-23 A. Formation of the Hemostatic Plug 1. The Platelet 2. Platelet Activation 29 29 A. Formation of the Hemostatic Plug 1. The Platelet major role to form mechanical plugs at the site of vessel injury to secrete regulators of the clotting process and vascular repair. In the absence of platelets, leakage of blood from rents in small vessels is common. Platelets are derived from megakaryocytes Megakaryocytes differentiate from the hematopoietic stem cell 30 30 15  2024-10-23 At the eight-nucleus stage, the cytoplasm becomes granular, the platelets are budded off the cytoplasm. A single megakaryocyte gives rise to ~ 4,000 platelets. In the nonactivated platelet the plasma membrane invaginates extensively into the interior of the cell Because the plasma membrane contains receptors and phospholipids the canalicular structure increases the membrane surface area the membrane surface area is potentially available for clotting reactions The platelet interior contains microfilaments and an extensive actin/myosin system. 31 31 Actin reorganization Platelets contain a large amount of actin An increase in the proportion of actin the actin filaments. Myosin Platelet activation causes Ca2+-dependent changes Platelet activation change the architecture of the plasma membrane. Normal platelet function is required for hemostasis. Inhibition of platelet function 32 32 16  2024-10-23 hyperactive platelets Calcium [World J Biol Chem. 1(9): 265] Long pseudopodia 33 33 Platelets contain three types of granules. electron-dense granules α-granule lysosomal granule 34 34 17  2024-10-23 A. Formation of the Hemostatic Plug 1. The Platelet 2. Platelet Activation Three fundamental mechanisms in platelet function : adhesion, aggregation, secretion. Adhesion sets off a series of reactions termed platelet activation, leads to platelet aggregation and secretion of platelet granule contents. refers primarily to the platelet-subendothelial interaction 35 35 von Willebrand factor is a protein synthesized in endothelial cells and megakaryocytes, von Willebrand factor is located in the subendothelial matrix, in specific platelet granules, and in the circulation bound to factor VIII. The platelet cell membrane contains glycoproteins (GPs) glycoproteins bind to collagen and to von Willebrand factor, causing the platelet to adhere to the subendothelium. Binding to collagen by glycoprotein GPIa (integrin α2β1) causes the platelet to change its shape from a flat disk to a spherical cell. Binding of subendothelial von Willebrand factor by glycoprotein GPIb causes changes in the platelet membrane platelet membrane exposes GPIIb/IIIa (integrin αIIbβ3)- binding sites to fibrinogen and von Willebrand factor. 36 36 18  2024-10-23 FIGURE 43.1 Adhesion of platelets to the subendothelial cell layer. 37 37 The initial adherence of platelets sets off a series of reactions platelet activation results in more platelets being recruited and aggregated at the site of injury. because ADP is a potent platelet activator, after initial adherence, some of the platelets release the contents of their dense granules and their α-granules, with ADP release ADP released from the platelets and from damaged red blood cells binds to a receptor on the platelet membrane, ADP leads to the further unmasking of GPIIb/IIIa-binding sites. because ADP induces swelling of the activated platelets, promoting platelet/platelet contact, and adherence, Aggregation of platelets cannot take place without ADP stimulation. 38 38 19  2024-10-23 Fibrinogen is a protein that circulates in the blood is found in platelet granules. consists of two triple helices held together with disulfide bonds. Binding of fibrinogen to activated platelets is necessary for aggregation platelets adhere to one another by this mechanism. Cleavage of fibrinogen by thrombin produces fibrin monomers thrombin is activated by the coagulation cascade fibrin monomers polymerize and form a “soft clot.” through binding to a specific receptor on the platelet surface, Thrombin itself is a potent activator of platelets,. 39 39 Fibrinogen (magenta) – thrombin complex Fibrin 40 40 20  2024-10-23 FIGURE 43.2 Cleavage of fibrinogen results in clot formation. 41 41 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade Thrombus (clot) formation is enhanced by thrombin activation, is mediated by the complex interaction that constitutes the blood coagulation cascade. blood coagulation cascade consists primarily of proteins proteins serve as enzymes or cofactors they function to accelerate thrombin formation and localize it at the site of injury. All of these proteins are present in the plasma as proproteins (a kind of zymogens). These precursor proteins are activated by cleavage of the polypeptide chain at one or more sites. The key to successful and appropriate thrombus formation is the regulation of the proteases that activate these zymogens. 42 42 21  2024-10-23 FIGURE 43.3 The blood coagulation cascade. 43 43 44 44 22  2024-10-23 The proenzymes - factors VII, XI, IX, X, and prothrombin : serine proteases when activated by cleavage, serine proteases cleave the next proenzyme in the cascade. zymogen : an inactive precursor of an enzyme. the addition of an “a” to the name of the proenzyme factor IX is cleaved to form the active factor IXa The cofactor proteins including tissue factor, factors V and VIII, serve as binding sites for other factors. 45 45 Tissue factor the other blood coagulation cofactors an integral membrane protein integral membrane protein does not require cleavage for active function. a protein present in subendothelial tissue and leukocytes coagulation factor III a cell surface glycoprotein. the blood coagulation cascades 46 46 23  2024-10-23 catalytic event the coagulation protease cascades Factors V and VIII Protein S a vitamin K-dependent plasma glycoprotein Factors Va and VIIIa 47 47 Protein C autoprothrombin IIA is regulated by proteolytic cleavage a serine protease. a zymogen The activated form Activated protein C performs these operations by inactivating proteins Factor Va and Factor VIIIa. 48 48 24  2024-10-23 vasoconstrictors. Vasoconstriction = the narrowing of the blood vessels Serotonin, thromboxane A2 Platelet-derived growth factor 49 49 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation Activation of the blood coagulation cascade two different pathways one dependent on external stimuli (the extrinsic pathway) Another using internal stimuli (the intrinsic pathway) 50 50 25  2024-10-23 In the case of external trauma, factor VII binds to tissue factor factor VII autocatalyzes its own activation to factor VIIa. Factor VIIa activates factor X (to Xa) in the extrinsic pathway factor IX (to IXa) in the intrinsic pathway. Factor IXa activates factor X. All of these conversions require access to membranes and calcium; The γ-carboxylated clotting proteins 51 51 cofactors VIIIa and Va thrombin formation factors V, VIII, and XI activator cofactors, VIIIa and Va these factors are in the intrinsic pathway 52 52 26  2024-10-23 The major substrate of thrombin is fibrinogen (magenta color) The major substrate of thrombin is hydrolyzed to form fibrin monomers fibrin monomers undergo spontaneous polymerization to form the fibrin clot. Cross-linking requires factor XIIIa (cyan color) factor XIIIa is activated by thrombin cleavage of factor XIII. 53 53 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation 1. Cross-Linking of Fibrin 2. Factor Complexes 3. Vitamin K Requirement for Blood Coagulation 54 54 27  2024-10-23 C. The Process of Blood Coagulation 1. Cross-Linking of Fibrin Factor XIIIa catalyzes a transamidation reaction between glutamine and lysine side chains on adjacent fibrin monomers. Factor XIIIa is the only enzyme in the blood coagulation 55 55 serine protease serine residue at their active sites Serine a polar amino acid encoded by six codons (UCU, UCC, UCA, UCG, AGU and AGC) trypsin-like, chymotrypsin-like, subtilisin-like, elastase-like, kallikrein, cathepsin, etc Trypsin-like proteases at Lys or Arg Chymotrypsins at Phe, Tyr or Try Elastase-like proteases at Ala, Gly or Val 56 56 28  2024-10-23 FIGURE 43.4 57 57 C. The Process of Blood Coagulation 1. Cross-Linking of Fibrin 2. Factor Complexes the blood coagulation cascade, Factors VII, IX, X, and prothrombin contain a domain one or more glutamate residues are carboxylated to γ-carboxyglutamate 58 58 29  2024-10-23 FIGURE 43.5 59 59 Prothrombin and factor X γ-carboxyglutamate residues bind Ca2+ The Ca2+ forms a coordination complex the negatively charged platelet membrane phospholipids and the γ-carboxyglutamates localizing the complex assembly and thrombin formation to the platelet surface 60 60 30  2024-10-23 Cofactor Va contains a binding site for both factor Xa and prothrombin. Upon binding to the factor Va–platelet complex, prothrombin undergoes a conformational change, rendering it more susceptible to enzymatic cleavage. Binding of factor Xa to the factor Va–prothrombin–platelet complex prothrombin-to-thrombin conversion. Complex assembly accelerates the rate of this conversion Factor VIIIa binds factor IXa and factor X. once tissue factor is exposed by injury, it binds factor VIIa 61 61 Complex assembly enhances the rate of thrombin formation explosive thrombin formation is localized to the site of vascular injury 62 62 31  2024-10-23 C. The Process of Blood Coagulation 1. Cross-Linking of Fibrin 2. Factor Complexes 3. Vitamin K Requirement for Blood Coagulation (Fig. 43.5) The formation of the γ-carboxyglutamate residues on blood coagulation factors takes place in the hepatocyte Within the hepatocyte, vitamin K is reduced to form vitamin KH2 carboxylases add a carboxyl group to the appropriate glutamate residues in the proenzyme to form the carboxylated prothrombin. 63 63 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation D. Regulation through Feedback Amplification and Inhibition 64 64 32  2024-10-23 D. Regulation through Feedback Amplification and Inhibition 1. The Role of Thrombin in Regulation 2. Proteins S and C 3. Serpins 65 65 D. Regulation through Feedback Amplification and Inhibition 1. The Role of Thrombin in Regulation Thrombin a prothrombotic regulatory role (feedback amplification) an antithrombotic regulatory role (feedback inhibition). when thrombin stimulates its own formation by activating factors V, VIII, and XI, the prothrombotic action is initiated 66 66 33  2024-10-23 FIGURE 43.3 67 67 1. The Role of Thrombin in Regulation Thrombin promotes clot formation by activating platelet aggregation, stimulating the release of factor VIII from von Willebrand factor, cleaving factor XIII to factor XIIIa. Antithrombotic effects of thrombin result from its binding to an endothelial cell receptor called thrombomodulin. (Fig. 43.6) Thrombomodulin abolishes the clotting function of thrombin allows thrombin to activate protein C 68 68 34  2024-10-23 FIGURE 43.6 69 69 D. Regulation through Feedback Amplification and Inhibition 1. The Role of Thrombin in Regulation 2. Proteins S and C Protein C and its cofactor protein S serve to suppress the activity of the coagulation cascade. protein C forms a complex with protein S. Protein S anchors the activated protein C complex to the clot The activated protein C complex destroys the active blood coagulation cofactors factor VIIIa and Va stimulates endothelial cells 70 70 35  2024-10-23 D. Regulation through Feedback Amplification and Inhibition 1. The Role of Thrombin in Regulation 2. Proteins S and C 3. Serpins serine proteases serine protease inhibitors At least eight major inhibitors section III. F, fibrinolysis 71 71 Each inhibitor possesses a reactive site an ideal substrate for a specific serine protease a trap for that protease The bound serine protease a peptide bond a tight enzyme–inhibitor complex the serpin antithrombin III (ATIII) regulation of blood coagulation at the level of thrombin is critical. One molecule of ATIII irreversibly inactivates one molecule of thrombin 72 72 36  2024-10-23 ATIII–thrombin complex formation is enhanced in the presence of heparin. Heparin is a glycosaminoglycan in the secretory granules of mast cells in the loose connective tissue Heparin binds to lysyl residues on ATIII accelerates its rate of binding to thrombin [J Biol Chem 262,8061] 73 73 an allosteric alteration in ATIII The formation of the ATIII–thrombin complex releases the heparin molecule Thrombin The ATIII–heparin complex 74 74 37  2024-10-23 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation D. Regulation through Feedback Amplification and Inhibition E. Thromboresistance of Vascular Endothelium Endothelial cells nonthrombogenic surface 75 75 Endothelial cells synthesize prostaglandin I2 (=prostacyclin, PGI2) and nitric oxide vasodilators and inhibitors of platelet aggregation. PGI2 synthesis Heparan sulfate is a glycosaminoglycan similar to heparin that potentiates antithrombin III accelerates the inactivation of thrombin 76 76 38  2024-10-23 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation D. Regulation through Feedback Amplification and Inhibition E. Thromboresistance of Vascular Endothelium F. Fibrinolysis propagation of the clot switching off blood coagulation turning on fibrinolysis. Fibrinolysis the degradation of fibrin Plasmin formed from its zymogen, plasminogen Zymogen, a proenzyme 77 77 Plasminogen a single-chain glycoprotein of 92kDa 792 amino acids five kringle domains mediate the specific binding to fibrin cleaved by either tissue-type plasminogen activator or urokinase plasminogen activator a circulating serum protein that has a high affinity for fibrin plasmin the zymogen form of plasminogen degrades fibrin clots 78 78 39  2024-10-23 plasminogen activators. serine proteases zymogen form plasminogen factor XIa and XIIa The conversion of plasminogen to plasmin by plasminogen activators 79 79 Activated protein C the release of plasminogen activator from tissues an inhibitor of plasminogen activator Plasminogen activator release the circulating plasmin Clot-bound plasmin plasminogen binding to 80 80 40  2024-10-23 This mechanism allows for dissolution of fibrin in pathological thrombin or oversized hemostatic plugs, prevents degradation of fibrinogen in the circulating blood. 81 81 endogenous plasminogen activators Tissue plasminogen activator Single-chain urokinase Streptokinase 82 82 41  2024-10-23 In vivo, physical stress, hypoxia, and large numbers of low- molecular-weight organic compounds promote increased synthesis release of Tissue plasminogen activator and Single-chain urokinase from tissues into the blood. The balance between release of plasminogen activators, the availability of fibrin, and inhibitors of the activators and plasmin 83 83 FIGURE 43.7 Regulation of plasmin activation. 84 84 42  2024-10-23 III. Plasma Proteins Maintain the Integrity of the Circulatory System A. Formation of the Hemostatic Plug B. The Blood Coagulation Cascade C. The Process of Blood Coagulation D. Regulation through Feedback Amplification and Inhibition E. Thromboresistance of Vascular Endothelium F. Fibrinolysis G. Regulation of Fibrinolysis Antiactivators 85 85 a fibrin clot The clot-bound plasmin plasmin is inactivated by α2-antiplasmin and α2-macroglobulin the fibrin network catalyzes both initiation and regulation of fibrinolysis. [email protected] 86 86 43