Transcript Secondary Hemostasis Coagulation Factors

Secondary Hemostasis
Coagulation Factors
Ahmad Sh. Silmi Msc, FIBMS
IUG
MT department
Coagulation System
 Composed of 14 coagulation factors (serine proteases) which are
interdependent (Factors I through XIII – there is no Factor VI – and PK
and HMWK)
 Inactive form of each is an enzyme precursor which is usually
designated by a Roman numeral but also given a name – Ex. Factor I
fibrinogen. Numbers correspond to order of discovery NOT order in
cascade.
 Active forms are usually designated by the letter “a” after the Roman
numeral and may also have a different name – Ex. Ia Fibrin
 Cofactors are needed for many reactions in the cascade – Ex.
Calcium, platelet factor 3 (PF3)
 Each molecule must be present in sufficient quantity as well as
functioning normally
 Final product is fibrin mesh or clot which completely stops bleeding
 Secondary hemostasis
 Slow contraction and lysis of the clot occurs
Coagulation factors
Coagulation Factors
Extrinsic
Cofactor
Substrate
Intrinsic
Enzyme
III
VII
Cofactor
Substrate
Common
Enzyme
Cofactor
Substrate
V
I
Enzyme
VIII
IX
II
HMWK
XI
X
XII
XIII
PK
Extrinsic
Intrinsic
Common
Cofactor
Mineral
CarrierOther
Cofactor
Mineral
CarrierOther
Cofactor
Mineral
CarrierOther
III
IV
PF3
VIII
IV
PF3
V
IV
PF3
vWF
HMWK
VI
Coagulation Factor I
 Fibrin Zymogen
 Customarily called
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fibrinogen
MWT = 340K (D)
Half-life 4 – 6 days
Mean plasma concentration
= 200 – 400 mg/DL
Glycoprotein
Found in PLT a-granules
Mirror image dimer: a, b, g
polypeptides linked by disulfide bonds
Primary substrate for
thrombin
Substrate for plasmin
Graphic accessed at URL http://www.sigmaaldrich.com/img/assets/27040/fibrinogen-cleave.jpg, 2008.
Coagulation Factor II
 Thrombin Zymogen
 Customarily called thrombin
 MWT = 71.6K (D)
 Half-life 2 - 4 days
 Mean plasma concentration =
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10 mg/DL
Vitamin K Dependent!!!!!!!!
Glycoprotein
Found in PLT a-granules
Mirror image dimer: a, b, g
polypeptides linked by disulfide bonds
Primary substrate for thrombin
Substrate for plasmin
SERINE PROTEASE!!!!!!!!!!
Graphic accessed at URL http://www.sigmaaldrich.com/img/assets/23640/Prothrombin_Image.gif, 2008.
Coagulation Factor III
 a.k.a Tissue Factor
 Synonymous with tissue
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thromboplastin, a crude
mixture of TF and
phospholipid
MWT = 44K (D)
Half-life – insoluble
Mean Plasma
concentration = Noncirculating
Lipoprotein
Constitutive lipoprotein of
subendothelium
Procoagulant
Graphic accessed at URL
http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb75_1.html, 2008.
Coagulation Factor IV
 a.k.a. ionic calcium, an
essential mineral
 MWT = 40 (D)
 Half-life – N/A
 Mean plasma
concentration 8 – 10
mg/dL
Graphic accessed at URL
http://www1.istockphoto.com/file_thumbview_approve/1010778/2/istockphoto_1010778_calcium_suppleme
nts.jpg, 2008.
Graphic accessed at URL http://www.clarian.org/ADAM/doc/graphics/images/en/18122.jpg. 2008.
Coagulation Factor V
 a.k.a. labile factor, a.k.a
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proaccelerin
At one time identified as factor
VI
Subtrate for thrombin and Xa
MWT = 330K
Half-life = 0.5 – 1.5 days
Mean plasma concentration = 1
mg/dL
25% of available concentration
stored in PLT a-granules
 Constitutional deficiency
of the factor results in
Owren’s disease also
known as parahemophilia.
 Cofactor for prothrombinase
complex
Graphic accessible at URL http://blood.uvm.edu/lab/domains.jpg. 2008.
Graphic accessed at URL http://blood.uvm.edu/lab/domains.jpghttp://blood.uvm.edu/lab/domains.jpg, 2008.
Factor 5 gene
Coagulation Factor VI
 DOES NOT EXIST!!!!!!
Coagulation Factor VII
 a.k.a Stable Factor
 Customarily called Factor VII
 MWT = 50K (D)
 Half-life 5 – 8 hours
 Mean plasma concentration =
0.05 mg/DL
 Vitamin K dependent
Glycoprotein
 Circulates as a zymogen and
in low quantities of active
form
 SERINE PROTEASE!!!!!!!!!!
Graphic accessed at URL http://path.upmc.edu/cases/case119/dx.html, 2008.
Coagulation Factor VIII
 a.k.a Antihemophilic Factor (AHF)
 MWT 330K (D)
 Plasma half-life = 8 – 12 hours
Very labile unless bound to vWF
 Individuals with von Willebrand
disease have both diminished
vWF and VIII activity levels
 Individuals with hemophilia A
have low VIII activity but normal
vWF levels
 Plasma concentration = 0.01 mg/dL
 Travels in plasma as a
heterodimer glycoprotein
complexed to vWF
 Thrombin substrate
 Cofactor for TENASE complex

Graphic accessed at URL http://www.uq.edu.au/vdu/VWF.gif, 2008.
Coagulation Factor IX
 a.k.a. Christmas Factor
Deficiency results in
Hemophilia B
MWT = 57K (D)
Half-life 1 - 3 days
Mean plasma concentration =
0.3 mg/DL
Activated by TF:VIIa complex
and XIa
Vitamin K Dependent!!!!!!!!
SERINE PROTEASE!!!!!!!!!!
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Graphic accessed at URL http://dbb.urmc.rochester.edu/bcbp/members/images/fay2.gif, 2008.
Coagulation Factor X
 a.k.a. Stuart-Prower factor
 MWT = 58.8K (D)
 Half-life 2 – 2.5 days
 Mean plasma
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concentration = 1 mg/dL
Activated by TENASE
complex and TF:VIIa
complex
Cofactor for
prothrombinase complex
Vitamin K
Dependent!!!!!!!!
SERINE PROTEASE!!!!!!!!!!
Graphic accessed at URL http://en.wikipedia.org/wiki/Factor_X, 2008.
Coagulation Factor XI
 SERINE PROTEASE!!!!!!!!!!
Graphic accessed at URL http://www.haemtech.com/images2/XIa.jpg, 2008.
Coagulation Factor XII
 a.k.a. Hageman Factor
 MWT = 84K (D)
 Half-life 2 – 3 days
 Mean plasma
concentration = 2 – 4
mg/DL
 Activated in vitro by
contact with negatively
charged surfaces
 SERINE
PROTEASE!!!!!!!!!!
Graphic accessed @ http://www.blackwellpublishing.com/korfgenetics/jpg/300_96dpi/Fig17-1.jpg, 2008.
COAGULATION FACTOR XIII
 a.k.a. Fibrin Stabilizing
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Factor
MWT = 320K (D)
Half-life 3 - 6 days
Mean plasma concentration
= 1 - 2 mg/DL
Transglutaminase
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“mortar” for fibrin
strands/mesh
a unit manufactured by
megakaryocytes; b unit
manufactured by
hepatocytes
 Thrombin substrate
Graphic accessed at URL http://www.haemtech.com/images2/Factor%20XIII.jpg, 2008.
High Molecular Weight Kininogen
 a.k.a. Fitzgerald Factor
 MWT = 120K (D)
 Half-life 6.5 days
 Mean plasma
concentration = 5 mg/DL
 Bound in circulation to
PK
 Monomeric a-globulin
Graphic accessed at URL http://journals.prous.com/journals/dnp/20001304/html/dn130213/images/Heit_f1.gif,
Prekallikrein
 Also known as Fletcher
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Factor
Half-life = 1.5 days
MWT = 85K (D)
Precursor of plasma
kallikrein
PK activated by activated
Hageman factor

Does not required ionized
calcium
 SERINE
PROTEASE!!!!!!!!!!
Platelet Factor 3 (PF 3)
 a.k.a. Phosphotidyl
serine (phospholipid)
 Functions as an assembly
molecule for coagulation
 Platelet derived
von Willebrand Factor (vWB)
 Multimeric glycoprotein
 Parts made in endothelial
cells and mekaryocytes
 Stored in endothelial cells
(Weibel-Palade Bodies)
and PLT a-granules
 Circulate in plasma
concentrations 7 – 10
mg/mL
 Ligand for PLT receptor
Ib/IX

See vWB/VIII complex
VITAMIN K DEPENDENCY
 Lipophilic, hydrophobic vitamin
needed for the posttranslational
modification of coagulation
factors II, VII, IX, AND X

Quinone found in green, leafy
vegetables, fish, liver and
produced by intestinal organisms
B. fragilis and E. Coli.
 Addition of second carboxyl
group to the g carbon of glutamic
acid residues near the terminal
end of II, VII, IX, and X

Creates a pocket for Ca++ that
promotes phospholipid binding
 Vitamin K deficiency or presence
of warfarin (vitamin K
antagonist) renders II, VII, IX, X
unable to participate in
coagulation reactions.
II
VII
IX
X
SERINE PROTEASES
 Endopeptidases which
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hydrolyze arginine or lysine
peptide bonds of zymogens
Important amino acid in
active site = serine
Proteolytic activity controlled
by serpins
Clannish: chymotrypsin-like,
the subtilisin-like, the
alpha/beta hydrolase, and
signal peptidase clans.
Participate in a wide range of
functions in the body,
including blood clotting,
immunity, and inflammation,
and digestion.
PROTHROMBINASE COMPLEX
 Important coagulation
cascade complex that
cleaves (“activates”)
prothrombin
 Composed of Xa, Va,
phospholipid (PLTderived) and ionic
calcium
 The first step in the
‘common’ pathway of
coagulation
vWF/FACTOR VIII COMPLEX
 VWF binds platelet
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glycoprotein (GP) Ib/V/IX to
provide platelet adhesion.
RGD (arginine-glycineaspartic acid) sequences bind
GP IIb/IIIa (αIIbβ3) to
promote platelet aggregation.
GP IIb/IIIa also binds RGD
sequences of fibrinogen.
A third VWF site binds
collagen.
VWF also provides a binding
site for coagulation factor
VIII.
VIII
TENASE COMPLEX
 Important coagulation
cascade complex that
cleaves (“activates”)
Factor X
 Composed of VIIIa, IXa,
phospholipid (PLTderived) and ionic
calcium
 The end product of the
‘instrinsic ’ pathway of
coagulation
X
Learning Objectives – Upon completion of required reading, after careful study,
and following this lecture, the student will be able to:
1.
2.
3.
4.
5.
6.
7.
Identify the name, Roman numeral designation, active form, site of
production, and hemostatic role for each of the clotting factors.
Describe then classify the coagulation factors as subtrates, cofactors,
or enzymes.
Evaluate the role of vitamin K in the production and function of
vitamin K dependent plasma clotting protein.
Characterize the nature and hemostatic function of the tenase, the
prothrombinase, and the vWB/VIII complexes.
Define these key terms: a) serine proteases, b) cofactor, and c) PF3.
Integrate the function of contact factors with ancillary systems of
hemostasis (e.g., fibrinolysis, inflammation, etc.)
Apply knowledge of the coagulation factors to correctly answer
clinical case study questions of hemostasis.
REFERENCES
 McKenzie, Shirlyn B (2004). Clinical Laboratory
Hematology. Pearson Prentice Hall. Chapter 35
 The Fritsma Factor at URL
http://www.fritsmafactor.com/
 Coagulation Disorders Tutorial by Indiana
University School of Medicine (2001) at URL
http://medsci.indiana.edu/c602web/602/c602web/
coagtut/docs/intro1.html
 Laboratory Tests On-line at URL
http://www.labtestsonline.org/