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Biochemistry: Vitamin K
Vitamin K
29
Chemistry
Graduate
05/16/2010

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Term
2 methyl 1,4 napthoquinone nucleus and lipophilic side chain is what vitamin?
Definition
Vit K
Term
Types of Vit K and sources?
Definition
K1: Phylloquinone (Plants)
K2: Menaquinone- n (microorganisms)
K3: Menadione (synthetic)
Term
Which form is synthetic vit K?
Definition
K3 Menadione
Term
Which is the most common form of K2 in animals?
Definition
Menaquinone 4 (MK-4) produced in the body, by processing of synthetic MENADIONE
Term
Vit K functions?
Definition
Vit K (reduced) --> co factor for γ-glutamylcarboxylase (in the ER)
- This enzyme γ-carboxylates glutamic residues in many VKD proteins.
Glutamic Acid residues (Glu) in VKD proteins converted to γ-carboxyglutamis acid residues (Gla)
Glu--> Gla
γ-carboxylation allows VKD proteins
to bind Ca
to fold properly and bind to cell membrane

ALSO
its necessary for
- coagulation and anticoagulation factors
- for osteocalcin binding to hydroxyapatite in bone
Term
Menaquinone 4 (where found)
Definition
Animal Tissues
Term
Phylloquinone (where found)?
Definition
Plants. MAIN dietary source
Term
Menaquinone 9 (where found)?
Definition
Intestinal flora
Term
Menadione (what form, corverted to what)?
Definition
Synthetic, converted to menoquinone 4
Term
What is meant by Vit K "Hook"?
Definition
γ-carboxylation allows VKD proteins to bind calcium and to fold properly and bind to cell membranes
Term
What is the reduced form of Vit K?
Definition
Vit K hydroquinone
Term
What is oxidized form of Vit K?
Definition
Vit K epoxide
Term
Warfarin and Vit K reductase?
Definition
Reductase steps are inhibited by warfarin.
Vit K cannot be converted to hydroquinone form required by γ-glutamyl carboxylase
Term
VKD protein?
Coagulation/anticoagulation
Calcified Tissue
Other proteins
Definition
~ 14 proteins
Coagulation/antigulation
- Factor II (prothrombin)
- Factors VII, IX, X
- Protein C, protein S
- γ carboxylase itself

Calcified tissue:
- Bone morphogenesis or formation
OSTEOCALCIN
- Bone matrix
Matrix Gla protein MGP
-- in bone, dentin, cartilage
-- inhibits tissue calcification

Other:
Gas 6: ligand for tyrosine kinase Axl
Protein Rich Gla protein *PRGP1, PRGP2
Term
VKD protein in Coagulation/Anticoagulation?
Definition
Coagulation/antigulation
- Factor II (prothrombin)
- Factors VII, IX, X
- Protein C, protein S
- γ carboxylase itself
Term
VKD protein in Calcified tissue?
Definition
Calcified tissue:
- Bone morphogenesis or formation
OSTEOCALCIN
- Bone matrix
Matrix Gla protein MGP
-- in bone, dentin, cartilage
-- inhibits tissue calcification
Term
Why is Carboxylation necessary for the action of VKD proteins?
Definition
Carboxylation results in Ca++ binding and a conformational change in the protein
Term
Osteocalcin
Definition
Calcium binding protein *HAS TO BE CARBOXYLATED or cannot bind to hydroxyapatite

- synthesized in osteoblast
- biomarker for bone formation
- 1,25 (OH)2D induces synthesis of osteocalcin by promoting transcription of its gene
- higher levels of Vit K required for complete γ carobxylation of osteocalcin that's needed for coagulation
Term
What is a biomarker for bone formation?
Definition
Osteocalcin
Term
Relationship with Vit K and Vit D?
Definition
High levels of Vit K needed to complete γ- carboxylation of osteocalcin needed for coagulation
1,25 (OH)2D directly induces synthesis of osteocalcin by promoting transcription of its gene
Term
Prothrombin time?
Definition
measures extrinsic pathway of coagulation
Term
INR (vit K)
Definition
International normalized ratio:
The INR is the ratio of a patient's prothrombin time to a normal (control) sample, raised to the power of the ISI value for the analytical system used.

- corrects for differences in thomboplastin sensitivities
Term
PIVKA-II (vit K)
Definition
Protein induced by vit K absensce factor II.

-serum [] of under γ carboxylated prothrombin
Term
ucOC (vitK)
Definition
Under-γ-carboxylated osteocalcin
Term
Clinical applicaton of Vit K?
Definition
Hemorrhagic disease in newborns--> poor transfer in placenta

Fat malabsorption
Antibiotic treatment
Bone mineral desnsity and osteoporosis:
- Low vit K or high levels of ucOC--> low bone mineral density (BMD)
- Vit K supplement reduce levels of ucOC
- supplement of menaquinon only maintained BMD in post menap. Female, while supplement with menaquinon + cholecalciferol increased BMD.
Term
Anticoagulant Drugs? (2)
Definition
Dicumarol and Warfarin
Term
People taking Coumadin : recommendations?
Definition
Watch how often you eat foods high in Vit K
Watch how much you eat of foods high in Vit K
keep vit K consistent day to day.
"high" no more that 1 serving
"mod high" no more than 3 servings/d
Term
Foods High in Vit K?
Definition
Kale
Spinach
Turnip greens
Collard greens
Swiss chard
parsley RAW
mustard greens
Term
Foods moderately high in Vit K?
Definition
spinach RAW
brussel sprouts
Green leaf lettus
broccoli RAW
Endive, romain lettuce RAW
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