Coagulation and Anticoagulation Physical Process of Clotting Chemical

Coagulation and Anti-coagulation Ö Physical Process of Clotting Ö Chemical Process of Clotting Fibrin formation, Extrinsic and Intrinsic pathways, Amplification, Activation of Enzymes, Clot Localization Ö Inhibitors of Clotting Anti-platelets, anti-coagulants Ö Antithrombin Ö Heparin, Low molecular weight heparins, Heparin Pentasaccharide Structure, properties, biochemical mechanism Ö Heparin mimics 1/8/2022 MEDC 604 Anti-coagulants 1

Scanning Electron Micrograph of a Clot 1/8/2022 MEDC 604 Anti-coagulants 2

Physical Process of Clotting 1/8/2022 MEDC 604 Anti-coagulants 3

The Chemical Process of Clotting HMWK XII XI XIIa IX XIa VIII X IXa VIIIa Note: • IXa and VIIIa work together to convert X into Xa. • Xa and Va work together to convert II into IIa. • IIa works on a number of steps. • HMWK and TF are initiation points • CLOT is the end point II Xa V Va IIa Xa IIa VIIa TF X VII Desai, U. R. , VCU (2005) 1/8/2022 XIII Fibrinogen MEDC 604 Anti-coagulants Fibrin monomers XIIIa CLOT 4

Important Characteristics of Clotting Cascade Ö Activation of Enzymes Ö Amplification Ö Clot Localization 1/8/2022 MEDC 604 Anti-coagulants 5

Important Characteristics of Clotting Cascade Ö Activation of Enzymes f. Xa (Arg 323 -Ile 324) Ser 562 f. Xa, Va PL, Ca 2+ 1 f. Xa (Arg 274 -Thr 275) Prothrombin 1/8/2022 Thrombin MEDC 604 Anti-coagulants 6

Important Characteristics of Clotting Cascade Ö Amplification C C A E 1 E 2 D E 3 F A E 1 B D 1/8/2022 MEDC 604 Anti-coagulants F X E 4 G E 2 E 3 Y E 4 G 7

Regulation of Clotting Ö Natural Anticoagulants Antithrombin, Tissue Factor Pathway Inhibitor, Protein C Ö Natural Products as Anticoagulant Drugs Heparin-based anticoagulants Coumarin-based anticoagulants Tick anticoagulant peptide 1/8/2022 MEDC 604 Anti-coagulants 8

Heparin and Low molecular weight heparins Structure and sequence 1/8/2022 MEDC 604 Anti-coagulants 9

Pentasaccharide 1/8/2022 MEDC 604 Anti-coagulants 10

Structure of Antithrombin – Pentasaccharide Complex EHBS Lys 136 RCL Arg 133 Lys 132 helix D helix A Arg 129 D Lys 125 PBS E F G Arg 47 Arg 46 H helix P Lys 114 1/8/2022 A) MEDC 604 Anti-coagulants B) 11

Biochemical Mechanism of Heparin Action AT + H AT: H AT-E 1/8/2022 E + H MEDC 604 Anti-coagulants 12

Designing Heparin Mimics Ö Binding in the Pentasaccharide Binding Site Ö Binding in the Extended Heparin Binding Site 1/8/2022 MEDC 604 Anti-coagulants 13