Download vitamin full - WordPress.com

A
B1
C
B3
D
B2
K
B6
B12
E
STRUKTUR, FUNGSI DAN MEKANISMENYA
VITAMIN




Merupakan senyawa organik
Merupakan komponen dari bahan pakan
Terdapat dalam jumlah kecil
Esensial untuk pertumbuhan normal suatu
jaringan, kesehatan, pertumbuhan dan
pemeliharaan
 Jika kekurangan menyebabkan gejala-gejala
spesifik
 Beberapa pada ternak tertentu disintesa oleh
tubuh (sebagian besar tidak disintesa dalam
tubuh)
lanjutan
 Digolongkan berdasarkan kesamaan fungsi
umum dalam metabolisme
 Umumnya terdapat di alam, dapat juga
disintesa
 Mempunyai ketahanan yang berbeda
terhadap cahaya, oksigen, asam, basa dan
panas
Ketahanan vitamin terhadap berbagai
pengaruh
Pengaruh
Cahaya
Vitamin yang
Vitamin yang
peka
stabil
Vit. A, Karoten,
Choline, as.
Vit.B1, B2, B6, Vit. Pantotenat
C, Vit. D, dan Vit E
Oksigen
Vit. A, Karoten,
Biotin, Vit.C dan
Vit. K
Gol. Vit.
Bkomplek,
as.nicotinat, Vit.D
dan Vit. E
Basa
Vit.B1, B2,as.
Pantotenat,
Vit.C,Vit. E dan
Vit.K
Vit. A, Karoten,
Vit.B6, Choline,
Biotin, Vit.D
Ketahanan vitamin terhadap berbagai
pengaruh (lanjutan)
Pengaruh
Asam
Panas
Vitamin yang
peka
Vit.A, Karoten,
Vit.B2,
as.pantotenant,
Vit.D
Vit.A, Vit. B1,B2,
Vit. C dan Vit. D
Vitamin yang
stabil
Vit. B1,B2,B12,
Biotin, Vit.C, Vit.E,
dan Vit. K
Karoten, Choline,
Biotin, Vit. E dan K
KLASIFIKASI VITAMIN
 Vitamin larut dalam lemak : A, D, E, K
 Vitamin larut dalam air:
B1 = tiamin
B2 = riboflavin
Asam pantotenat
Niasin = Niacinamide
Biotin
Folacin
B6 = Pyridoxine, Pyridoxal, Pyridoxamin
B12=Cyanocobalamin, Hydoxocobalamin,
Aquocobalamin
Choline
Vitamin C = Ascorbic acid, L-ascorbic acid
Perbedaan Vitamin larut dalam lemak
dan vitamin larut dalam air
Vitamin larut
dalam lemak
C,H,O
Vitamin larut
dalam air
C,H,O + N,S,Co
Pada tanaman,
tidak ada bentuk
provitamin
Peran fisiologis
Jaringan
tanaman, ada
bentuk
provitamin
Kontrol metabolis
Absorbsi
lemak
air
Komposisi kimia
Terjadinya
Transfer energi
Perbedaan Vitamin larut dalam lemak
dan vitamin larut dalam air
Penyimpanan
Ekskresi
Vitamin larut
dalam lemak
Dideposit dalam
lemak
Melalui feses
Vitamin larut
dalam air
Di seluruh sel
hidup
Terutama melalui
urine.
Kadang-kadang
ada dalam feses
karena ada
sintesis oleh
mikroba.
Perbedaan Vitamin larut dalam lemak
dan vitamin larut dalam air
Sifat Aktivitas
Kelainan
Vitamin larut
dalam lemak
A,D,K= Individual
E=Broad spectrum
Hypovitaminosis
Hypervitaminosis
Vitamin larut
dalam air
Broad spectrum
Hypovitaminosis
VITAMIN ALAMI
 Dalam bahan pakan jumlahnya sangat bervariasi dan
tidak ada satu bahan pakan yang mengandung
jumlah optimal untuk hewan.
 Semua vitamin dibuat di tanaman dan diperoleh
hewan apabila mengkonsumsi tanaman
 Hewan mengandung mikroorganisme yang sanggup
mensintesis vitamin larut dalam air, provitamin A dan
menaquinone (Vitamin K2)
 Vitamin B12 hanya bisa disintesis oleh mikroorganisme tertentu tidak bisa oleh tanaman
ataupun hewan
KESTABILAN VITAMIN
Kestabilan vitamin dipengaruhi juga oleh
adanya antivitamin seperti :
# Avidin yang ada pada putih telur akan
mengikat biotin
# Thiaminase pada ikan menghambat
tiamin
# l-amino-D-prolin pada flaxseed
membentuk komplek stabil dengan
pyridoxine
GENERAL VITAMIN STABILITY
VITAMIN
STABILITY CHARACTERISTIC
A
Oxidasi khususnya dengan Fe,Cu
D3
Oxidasi (kestabilan sedang)
E
Stabil dalam bentuk acetat, sangat
tidak stabildalam bentuk alcohol
K
Sangat tidak stabil
Tiamin
Sensitif terhadap oxidasi dan pH
GENERAL VITAMIN STABILITY
VITAMIN
STABILITY CHARACTERISTIC
Pyridoksin,
Kestabilan sedang
riboflavin
Pantotenat
Sensitif hidrolisis
Niasin
B12
Biotin
Asamfolat
Vitamin C
Hampirstabil
Kestabilan tinggi, beberapa hilang bila
kedaluwarsa
Hampir stabil
Kestabilan sedang, sensitif oxidasi dan
reduksi
Sangat tidak stabil dalam bentuk alami
VITAMIN LARUT DALAM LEMAK
Vitamin A (Retinol)
R=CH2OH
Retinol
R=CH2OH
Retinal
R=CH2OH
Asam Retinoat
Vitamin A (Retinol)
H3C
CH3
CH3
CH3
OH
CH3
Retinol
b - Carotene and Retinol
CH 3
CH 3
CH 3
CH 3
H3 C
CH 3
CH 3
CH 3
CH 3
Oxidation
H3 C
CH 3
CH 3
CH 3
O
C H
Retainal
CH 3
- 2H
H3 C
CH 3
CH 3
CH 3
CH 3
CH 2 OH
Retinol (Vitamin A)
CH 3
Fungsi Vitamin A
1.Rangsangan cahaya dari mata ke otak
2.Berperan dalam sel epitel
3.Mengontrol aktivitas tulang
The vision cycle
Opsin balok : rodopsin
Opsin kerucut : iodopsin
Defisiensi Vitamin A
1.Buta malam
2.Seroptalamia (pengeringan & iritasi
kornea, keruh dan mudah terinfeksi)
3.Terganggu sel
D2=Ergokalsiferol
Vitamin D
D3=Kholekalsiferol
Pro Vit D2 = ergosterol
Pro Vit D3 = 7 dehidrokholesterol
Fungsi Vitamin D
1. Proses absorpsi
2. Proses reabsorpsi
3. Deposisi
Defisiensi Vitamin D
1. Rakhitis
2. Osteomalasia
Vit E bentuk jenuh
Vitamin E
Alfatokoferol, Betatokoferol, Gamatokoferol,
Deltatokoferol
Vit E bentuk tidak jenuh
Alfatokotrienol, Betatokotrienol, Gamatokotrienol,
Deltatokotrienol
1. Reproduksi
Fungsi Vitamin E
2. Generasi
3. Hati dan Metabolisme
4. Memperbaiki absorpsi Fe
5. Antioksidan
Defisiensi Vitamin E
1. Kemunduran Reproduksi
2. Gangguan permeabilitas
3. Kerusakan otot
Vitamin K
K1 = Filoquinon
K2 = Menaquinon
K3 = Menadion
Fungsi Vitamin K
Koagulasi darah dengan mengaktifkan
prothrombin (sintesis prothrombin didalam
hati)
Thrombin Activation
vWF
WOUND
collagen
endothelium

platelet
Va 
Xa
Pro-Thrombin
Thrombin
S
SS
S COOH
COOH
  
Ca Ca
 
 
Gla Gla
 
Gla Gla
PL surface
ProNH2
proteolytic cut
C
i
r
c
u
l
a
t
i
o
n
NH2
Fibrinogen + thrombin------------- Fibrin + Peptida
Defisiensi Vitamin K
1. Pembekuan darah terganggu
FUNGSI BIOKEMIS VITAMIN
Vitamin
Fungsi Biokemis
A
-Essensial
u/ pembentukan rhodopsin (melihat dlm
gelap), pada reproduksi tikus,u/memelihara plasenta
½ periode kebuntingan yang kedua, Sintesa
mukopolisakarida dan proses pembentukan tulang
D
-Mempengaruhi
E
antioksidan,berperan pada pernafasan
jaringan,fosforilsasi dari kreatin fosfat, sintesa
as.askorbat dan metabolisme a.a yg mgd belerang
K
Proses pembekuan darah (sintesa prothrombin &
bbrp protein plasma), pembentukan RNA
metabolisme Ca dan P
(memperbaiki ossifikasi dan deposisi dalam kartilago
dan kulit telur) serta menaikkan aktivitas enzim
phytase pd usus tikus
VITAMIN LARUT DALAM
AIR
Glycogenolysis
Glc
PP a
vit B6
G1P
Glycogen
Ala
Asp
Glycolysis
PPP
G6P
ALT
vit B6
R5P
TK
vit B1
G3P
Pyr
PDH
vit B1,B2,B3
AST
vit B6
OA
TCA
cycle
SCoA
aKG
Acetyl-CoA
vit B6
Glu
aKGDH
vit B1,B2,B3
33
Vitamin B1




Thiamine pyrophosphate (TPP)
Thiamine - a thiazole ring joined to a
substituted pyrimidine by a methylene bridge
Thiamine-PP is the active form
TPP is involved in carbohydrate metabolism
It catalyzes decarboxylations of alpha-keto
acids and the formation and cleavage of alphahydroxyketones
Thiamine Pyrophosphate




Reactions and rationale
Yeast pyruvate decarboxylase, acetolactate synthase,
transketolase, phosphoketolase
All these reactions depend on accumulation of
negative charge on the carbonyl carbon at which
cleavage occurs!
Thiamine pyrophosphate facilitates these reactions
by stabilizing this negative charge
The key is the quaternary nitrogen of the thiazolium
group
Riboflavin and the Flavins





Vitamin B2
All these substances contain ribitol and a flavin or
isoalloxazine ring
Active forms are flavin mononucleotide (FMN)
and flavin adenine dinucleotide (FAD)
FMN is not a true nucleotide
FAD is not a dinucleotide
But the names are traditional and they persist!
Flavin Mechanisms




Flavins are one- or two-electron transfer agents
Name "flavin" comes from Latin flavius for
"yellow"
The oxidized form is yellow, semiquinones are
blue or red and the reduced form is colorless
Study the electron and proton transfers in Figure
18.22
Other transfers are possible!
Coenzyme A
Pantothenic acid (vitamin B3) is a component of
Coenzyme A
 Functions:
 Activation of acyl groups for transfer by
nucleophilic attack
 activation of the alpha-hydrogen of the acyl group
for abstraction as a proton
 Both these functions are mediated by the
reactive -SH group on CoA, which forms
thioesters
Nicotinic Acid and the
Nicotinamide Coenzymes
aka pyridine nucleotides
 These coenzymes are two-electron carriers
 They transfer hydride anion (H-) to and from
substrates
 Two important coenzymes in this class:
 Nicotinamide adenine dinucleotide (NAD+)
 Nicotinamide adenine dinucleotide phosphate
(NADP+)
Nicotinamide Coenzymes




Structural and mechanistic features
The quaternary nitrogen of the nicotinamide
ring acts as an electron sink to facilitate
hydride transfer
The site (on the nicotinamide ring) of hydride
transfer is a pro-chiral center!
Hydride transfer is always stereospecific!
Be sure you understand the pro-R, pro-S
designations
Last Notes on Nicotinamides
 Nicotinamide was first isolated in 1937 by
Elvehjem at the University of Wisconsin
 Note similarities between structures of
nicotinic acid, nicotinamide and nicotine
 To avoid confusion of names (and functions!),
the name niacin (for nicotinic acid vitamin) was
suggested by Cowgill at Yale.
Biotin




"Chemistry on a tether"
Biotin functions as a mobile carboxyl group
carrier
Bound covalently to a lysine
The biotin-lysine conjugate is called biocytin
The biotin ring system is thus tethered to the
protein by a long, flexible chain
Biotin Carboxylations




Most use bicarbonate and ATP
Whenever you see a carboxylation that requires
ATP and CO2 or HCO3-, think biotin!
Activation by ATP involves formation of carbonyl
phosphate (aka carboxyl phosphate)
Carboxyl group is transferred to biotin to form Ncarboxy-biotin
The "tether" allows the carboxyl group to be
shuttled from the carboxylase subunit to the
transcarboxylase subunit of ACC-carboxylase
Folic Acid
Folates are donors of 1-C units for all oxidation
levels of carbon except that of CO2
 Active form is tetrahydrofolate (THF)
 THF is formed by two successive reductions of
folate by dihydrofolate reductase
 Know how to calculate oxidation states of C!
Vitamin B6




Pyridoxine and pyridoxal phosphate
Catalyzes reactions involving amino acids
Transaminations, decarboxylations, eliminations,
racemizations and aldol reactions
See Figure 18.26
This versatile chemistry is due to:
 formation of stable Schiff base adducts
 a conjugated electron sink system that stabilizes
reaction intermediates
Pyridoxal Phosphate
Mechanisms
 Figure 18.27 is a key figure - relate each
intermediate to subsequent mechanisms
 Appreciate the fundamental difference
between intermediates 2-5 and 6,7
Vitamin B12
Cyanocobalamin
 B12 is converted into two coenzymes in the
body:
 5'-deoxyadenosylcobalamin
 methylcobalamin
Vitamin B12
Cyanocobalamin
 Dorothy Hodgkin determined the crystal
structure of B12 in 1961 - at the time it was the
most complicated structure ever elucidated
by X-ray diffraction and she won a Nobel
prize
 Most striking feature - the C-Co bond length
of 0.205 nm (2.05 A) - an essentially covalent
bond
B12 Function & Mechanism
See Figures 18.28-18.29
 B12 catalyzes 3 kinds of reactions:
 Intramolecular rearrangements
 Reductions of ribonucleotides to
deoxyribonucleotides
 Methyl group transfers (assisted by
tetrahydrofolate )
FUNGSI BIOKEMIS VITAMIN
Vitamin
B1 (Tiamin)
Fungsi Biokemis
-Koenzim
pd proses dekarboksilasi ketoacid (Co : as.
Piruvat)
B2 (Riboflavin)
-Dlm
bntk flavin mononucleatid (FMN) dan flavin
adenin dincleatid (FAD) bertindak sbg gugus
prostetik dari bbrp enzim dlm r. oksidasi-reduksi dlm
tubuh
B6 (Pyridoxine)
Koenzim proses dekarboksilasi,deaminasi dari
serine dan threonine, transaminasi, transulfrasi, &
transfer a.a. dalam sel
Nicotinaminde
(Niasin)
-komponen koenzim NAD dan NADP dalam
transport hidrogen
FUNGSI BIOKEMIS VITAMIN
Vitamin
Fungsi Biokemis
As. Panthotenat
-Merupakan
gugus prostetik koenzim A yg mpy
fungsi dlm r. acetilasi pada KH, lemak dan
metabolisme a.a.
Vit. B12
-Koenzim
Choline
Pembentukan dan pemeliharaan sel-sel tubuh, sbg
methyldonator
Vit. C
Pembentukan kolagen,dibutuhkan dlm perb. As.folat
mjd tetra hydrofolic acid, proses hydroxylasi
prolin,lysine & anilin / fungsi normal fisiologis.
sintesa as. Nukleat (RNA), pembentukan
gugus methyl pada thyamine
GEJALA DEFISIENSI VITAMIN
VITAMIN
GEJALA DEFISIENSI
A
Keratinisasi
Xeropthalmia
D
Ricket
Osteomalacia
E
Muscular distropy
Exudativediathesis
Encephalomalcia
K
Terhambatnyaproses pembekuan
darah
GEJALA DEFISIENSI VITAMIN
VITAMIN
GEJALA DEFISIENSI
Tiamin (B1)
Anorexsia, polineuritis, nafsu mkn turun
Riboflavin
Curled toe paralysis, nafsu mkn turun,diare
As.pantotenat
Pertumbuhan badan & bulu terhenti, Dermatitis
(pelupuk mata,sudut mulut,kaki),goose step(babi)
Niasin
Pellagra (dermatitis, diare, dementia), anemia
nafsu mkn turun,pertumbuhan terganggu
Pyridoksin
Convulsi (kekejangan), anemia, nafsu mkn turun
Biotin
Perosis, dermatitis
Asam folat
Anemia, pertumbuhan terhambat, bulu jelek,
depigmentasi, perosis
Kholin
Hati berlemak, perosis (babi),gangguan pertumbuhan
& pembtk kuning telur
Pertumbuhan yg tidak baik,Anemia, kegagalan fungsi
reproduksi
Cobalamin
KERACUNAN VITAMIN
Vitamin
Safe Upper Feed
Safe Upper
Level(unit/kg
Level+ Normal
pakan)
Level
A
80.000 IU/kg
10
D3
10.000 IU/kg >60 d
3-4
50.000 IU/kg < 20 d
20-30
E
1000 IU/kg
20-30
K
2000 mg/kg
1000