Proteolysis/Coagulation Flashcards
What is Factor IIa’s other name?
Thrombin
How does pepsinogen activate into pepsin?
Autocatalysis due to pH
Mechanism for pepsinogen activation
At lower pH, Asp becomes protonated and salt bridges are broken
What is enteropeptidase?
A protease secreted in the small intenstine
How is trypsin activated?
Enteropeptidase cleaves trypsinogen at Lys-6/Ile-7
Which zymogens can trypsin activate?
Chymotrypsinogen, procarboxypeptidase, and proelastase
Four forms of chymotrypsin
Chymotrypsin -> pi-chymotrypsin -> delta-chymotrypsin -> alpha-chymotrypsin
What is a secondary safety mechanism against trypsin activation?
Pancreatic Trypsin Inhibitor
What does alpna-1 antitrypsin inhibit?
Elastase
What number is tissue factor?
Factor 3
What does thrombin stimulate in the cascade?
Factors VIII and V
What does Protein C inactivate?
Factors V and VIII
Which final factor crosslinks fibrin strands to strengthen the clot?
Factor XIIIa
Intrinsic to Extrinsic Pathway: Factors XII, IX, X can activate…
Factor VII
How does Factor XIIIa work?
It’s a transglutaminase. Crosslinks glutamine and lysine sidechains
What serves as a carrier for Factor VIII?
von Willebrand Factor
What does vWF serve as a link between?
platelet surface glycoproteins and exposed ECM
What does kallikrein cleave to downregulate the clotting process?
Active factor XII
What activates Protein C?
thrombin
What is AT3?
Antithrombin III; serine protease inhibitor
AT3 inhibits…
thrombin, XIIa, XIa, IXa, and Xa
What enhances the rate of thrombin-AT3 complex formation to inhibit thrombin?
Heparin
What activates pasminogen into plasmin?
Tissue Plasminogen Activator
What does plasmin do?
Cleaves fibrin and dissolves the clot
