VITAMIN

1
Vitamin D
uv irradiation
Vitamin D2 (ergocalciferol)
Ergosterol (plant sterol)
uv irradiation
7-Dehydrocholesterol (animals)
Vitamin D3 (cholecalciferol)
in liver
Cholesterol
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
2
25 - Hydroxycholecalciferol (major form ??? vit
D3)
Active form 1,25 - Dihydroxycholecalciferol
(calcitriol)
Function ?????? metabolism ??? Ca2 ???
phosphate
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
3
Cholecalciferol ( Ergosterol )
small intestine
Specific vitamin D - binding protein
blood circulation
liver
Cholecalciferol ( inactive )
reduced levels ??? PTH stimulate
specific D3 - 25 - hydroxylase
25 - Hydroxy - D3 25 - (OH) D3
specific D3 - 24 - hydroxylase (kidneys, intestin
e, placenta ??? cartilage)
( major circulating form ??? vitamin D )
specific 25-hydroxy-D3 -1a - hydroxylase
1,25 - Dihydroxy - D3 1,25 - (OH)2 D3 ( active
)
( kidneys, bone ??? placenta )
24,25 - Dihydroxy - D3
( inactive )
4
????? Murray et al, 1996
5
????????????????????Vitamin D3 ?????? Active Form
Cholecalciferol (vitamin D3)
liver
Feedback inhibition
25-Hydroxycholecalciferol
kidney
activation
Parathyroid hormone
1,25-Dihydroxycholecalciferol
intestinal epithelium
Calcium Calcium Alkaline
inhibition
binding stimulated phosphatase
protein ATPase
Ca2gt10mg
Intestinal absorption ??? Ca2
Plasma Ca2concentration
6
Calcium Ion ( Ca2)
????????????????? Ca5(PO4)3OH (hydroxyapatite)
???????????????????????????????? ???????????
1. ????????????????????? 2.
?????????????????? ( blood clotting )
3. ???????? nerve impulse Ca2
?????? cell ?????? 1.2 mM ????????????
hormones ?????? parathyroid hormone, vitamin D
??? calcitonin
7
Hormone ???????????????? Ca2???????
1. Parathyroid hormone polypeptide hormone
(84 amino acid residues) ???????? parathyroid
gland ????????????? Ca2?? plasma ??? 2. Vitamin
D 3. Calcitonin polypeptide hormone (33 amino
acid residues) ???????? thyroid gland
8
??????????PTH,Vitamin D ???Calcitonin ???????????
Metabolism ??? Ca2
Small intestine
PTH, VitaminD

Ca2concentration I? plasma
PTH


Vitamin D


Calcitonin
-
-
Bone
Kidney
9
Vitamin E
a - Tocopherol ( 5,7,8 - trimethyl tocol ) vit
E ???????? biological acitivity ??????
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
10
Vitamin E
small intestine
Chylomicrons
blood circulation
Vitamin E
liver
VLDL
blood circulation
Vitamin E
Adipose tissue ( ?????????????????? vit E)
tissues
11
????????????????????????? lipophilic
compound vitamin E ?????????????

• Cellular membranes
• Fat deposits
• Circulating lipoproteins

12
?????????? Vitamin E
1. ???? antioxidant ????? free radicals 2.
?????????????? peroxidation ???
polyunsaturated membrane fatty acids
13
???????? Free Radical
ROO ToCOH
ROOH ToCO
peroxyl radical
phenoxyl radical
phenolic H
ROOH Non - free radical
product
1. ROO
ToCO
ToCOH a - Tocopherol
Vitamin C ToCO ToCOH
2.
????? Murray et al, 1996
14
VITAMIN K

• Vitamin K1 ( phylloquinone ) ?? green vegetables
• Vitamin K2 ( menaquinone ) ?? intestinal bacteria
• Vitamin K3 ( menadione ) ????synthetic vitamin

15
????? Voet and Voet, 1995
16
Absorption ??? vitamin K
small intestine
blood circulation
bile salts ??? lipids
Chylomicrons
17
?????????? vitamin K ???????????????????? blood
clotting proteins, factors II, VII, IX, X,
protein C ???protein S
LIVER
Factors II, VII, IX, X, protein C ???
protein S ????????????? inactive precursor
proteins
18
Inactive clotting factors
posttranslational modification
Active clotting factors
Posttranslational modification
Specific glutamic residues
g - carboxyglutamate
carboxylase, vitamin K ???? cofactor
19
O
NH
CH
C
CH2
R group side chain ??? glutamate
CH2
COO -
carboxylase ( vitamin K )
HCO3-
(CO2)
O
NH
CH
C
a
CH2
carboxyglutamate
g -
b
CH
g
COO -
-OOC
Posttranslational modification ??? glutamate
20
????????? Ca2 ??????? g - Carboxyglutamate ???
Prothrombin
Ca2
O
O -
O
- O
C
C
CH
CH2
CH
N
C
H
O
21
Factor II ( preprothrombin )
posttranslational modification
Prothrombin
(g - carboxyglutamate residues ???? calcium ion
chelators)
activated factor X ( Xa )
????????? chelation ??? calcium ??????
prothrombin ???????????????? phospholipids ??
membranes ????????????????
Thrombin
Fibrin ( insoluble fibrous network )
Fibrinogen ( soluble plasma protein )
22
Vitamin K Cycle ?????
carboxylase (vit K dependent)
monooxygenase
2,3-epoxide
hydroquinone (reduced form)
dithiol reductant
2,3-epoxide reductase
reductase

Competitive inhibitors
quinone form
????? Murray et al, 1996