protein function- basics/clotting Flashcards
Name the short term controls on enzyme activity
substrate and produce concentration
change in enzyme conformation
Allosteric regulators are…
list properties
multi subunit
2 conformations–> tense / relaxed
follow sigmoidal kinetics
can be activators or inhibitors
Name activators of phosphofructokinase
AMP
fructose-2,6- bisphosphate
Name inhibitors of phosphofructokinase
ATP
Citrate
H
What enzyme phosphorylate
kinases
What enzyme dephosphorylate
phosphatases
What is a zymogen
inactive form of an enzyme
What is role of alpha 1 anti trypsin
inhibits range of proteases
deficiency allows destruction of alveolar walls by elastase
Name two long term regulation
change rate of protein synthesis- enzyme induction or repression
change in rate of protein degradation- ubiquitin protease pathway
outline intrinsic pathway of clotting cascade
damage to endothelial cells FXI FIX FVIII FX Fv thrombin fibrin
outline extrinsic pathway of clotting cascade
trauma releases Tissue factor FIII FVII FX FV Thrombin fibrin
What factor do pathways converge ?
FX
What are the two key co factors?
FVIII
FV
What factor responsible for positive feedback?
FXIII
Describe the structure if prothrombin
serine protease C terminal
2 Kringle domains
carboxyglutamate domain
What is the role of the kringle domains
keep serine protease inactive
What is the role of the Gla domain
target it to appropriate site for activation
How is gla domain formed?
PTM in liver add COOH to glutamate
Describe the structure of fibrinogen
2 sets of tripeptides alpha beta gamma
3 globular domains linked by rods
n terminal regions of alpha and beta chains very negatively charged preventing aggregation
Describe process of clot formation
thrombin cleaves fibrinopeptides A + B from central globular domain of fibrinogen
globular domains at c terminal of beta and gamma interact with exposed sequences at n terminal of cleaved beta and alpha
clot forms
clot stabilised by cross links by formation of amide bonds
what enzyme is responsible is formation of crosslinks
transglutaminase activated by thrombin
What is haemophilia a caused by
missing/ reduced FVIII
How is the clotting process stopped
localisation of prothrombin - diluted by blood flow
digestion of factors by protein C
specific inhibitors e.g. antithrombin III (AT 3)
What activates protein C
thrombin binding to thrombomodulin receptor on endothelial cell
