STRUKTUR, FUNGSI DAN MEKANISMENYA

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1 STRUKTUR, FUNGSI DAN MEKANISMENYA
B1 C D B3 B2 K B6 STRUKTUR, FUNGSI DAN MEKANISMENYA E B12 VITAMIN

2 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)

3 lanjutan Vitamin 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

4 Ketahanan vitamin terhadap berbagai pengaruh
Vitamin yang peka Vitamin yang stabil Cahaya Vit. A, Karoten, Vit.B1, B2, B6, Vit. C, Vit. D, dan Vit E Choline, as. Pantotenat 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

5 Ketahanan vitamin terhadap berbagai pengaruh (lanjutan)
Vitamin yang peka Vitamin yang stabil Asam Vit.A, Karoten, Vit.B2, as.pantotenant, Vit.D Vit. B1,B2,B12, Biotin, Vit.C, Vit.E, dan Vit. K Panas Vit.A, Vit. B1,B2, Vit. C dan Vit. D Karoten, Choline, Biotin, Vit. E dan K

6 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

7 Perbedaan Vitamin larut dalam lemak dan vitamin larut dalam air
Komposisi kimia C,H,O C,H,O + N,S,Co Terjadinya Jaringan tanaman, ada bentuk provitamin Pada tanaman, tidak ada bentuk provitamin Peran fisiologis Kontrol metabolis Transfer energi Absorbsi lemak air

8 Perbedaan Vitamin larut dalam lemak dan vitamin larut dalam air
Penyimpanan Dideposit dalam lemak Di seluruh sel hidup Ekskresi Melalui feses Terutama melalui urine. Kadang-kadang ada dalam feses karena ada sintesis oleh mikroba.

9 Perbedaan Vitamin larut dalam lemak dan vitamin larut dalam air
Sifat Aktivitas A,D,K= Individual E=Broad spectrum Broad spectrum Kelainan HypovitaminosisHypervitaminosis Hypovitaminosis

10 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 mikro- organisme tertentu tidak bisa oleh tanaman ataupun hewan

11 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

12 GENERAL VITAMIN STABILITY
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

13 GENERAL VITAMIN STABILITY
STABILITY CHARACTERISTIC Pyridoksin, Kestabilan sedang riboflavin Pantotenat Sensitif hidrolisis Niasin Hampirstabil B12 Kestabilan tinggi, beberapa hilang bila kedaluwarsa Biotin Hampir stabil Asamfolat Kestabilan sedang, sensitif oxidasi dan reduksi Vitamin C Sangat tidak stabil dalam bentuk alami

14 VITAMIN LARUT DALAM LEMAK

15 R=CH2OH Retinol R=CH2OH Retinal R=CH2OH Asam Retinoat
Vitamin A (Retinol) R=CH2OH Retinol R=CH2OH Retinal R=CH2OH Asam Retinoat

16 Vitamin A (Retinol) Retinol

17 b - Carotene and Retinol
CH 3 CH CH CH 3 3 3 H C 3 CH 3 CH CH CH 3 3 3 CH 3 Oxidation CH CH O H C CH 3 3 3 3 C H CH Retainal 3 - 2H CH CH H C CH 3 3 3 3 CH OH 2 Retinol (Vitamin A) CH 3

18 Fungsi Vitamin A Rangsangan cahaya dari mata ke otak
Berperan dalam sel epitel Mengontrol aktivitas tulang

19 The vision cycle Opsin balok : rodopsin Opsin kerucut : iodopsin

20 Defisiensi Vitamin A Buta malam
Seroptalamia (pengeringan & iritasi kornea, keruh dan mudah terinfeksi) Terganggu sel

21 Pro Vit D2 = ergosterol Pro Vit D3 = 7 dehidrokholesterol
Vitamin D D2=Ergokalsiferol D3=Kholekalsiferol Pro Vit D2 = ergosterol Pro Vit D3 = 7 dehidrokholesterol

22 Fungsi Vitamin D 1. Proses absorpsi 2. Proses reabsorpsi 3. Deposisi
Defisiensi Vitamin D 1. Rakhitis 2. Osteomalasia

23 Vitamin E Vit E bentuk jenuh Alfatokoferol, Betatokoferol, Gamatokoferol, Deltatokoferol Vit E bentuk tidak jenuh Alfatokotrienol, Betatokotrienol, Gamatokotrienol, Deltatokotrienol

24 4. Memperbaiki absorpsi Fe
Fungsi Vitamin E 1. Reproduksi 2. Generasi 3. Hati dan Metabolisme 4. Memperbaiki absorpsi Fe 5. Antioksidan

25 1. Kemunduran Reproduksi 2. Gangguan permeabilitas 3. Kerusakan otot
Defisiensi Vitamin E 1. Kemunduran Reproduksi 2. Gangguan permeabilitas 3. Kerusakan otot

26 K1 = Filoquinon K2 = Menaquinon K3 = Menadion
Vitamin K K1 = Filoquinon K2 = Menaquinon K3 = Menadion Fungsi Vitamin K Koagulasi darah dengan mengaktifkan prothrombin (sintesis prothrombin didalam hati)

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28 Thrombin Activation Fibrinogen + thrombin  Fibrin + Peptida

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30 1. Pembekuan darah terganggu
Defisiensi Vitamin K 1. Pembekuan darah terganggu

31 FUNGSI BIOKEMIS VITAMIN
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 metabolisme Ca dan P (memperbaiki ossifikasi dan deposisi dalam kartilago dan kulit telur) serta menaikkan aktivitas enzim phytase pd usus tikus 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

32 VITAMIN LARUT DALAM AIR

33 Vitamins in Metabolic Pathways
Glycogenolysis Glc Glycogen G1P PP a vit B6 G6P Pyr G3P Glycolysis PPP R5P TK vit B1 ALT vit B6 Ala PDH vit B1,B2,B3 Acetyl-CoA AST vit B6 TCA cycle OA Asp Glu vit B6 Glc: glucose G6P: glucose-6-phosphate G3P: glyceraldehyde-3-phosphate Pyr: pyruvate PDH: pyruvate dehydrogenase Acetyl-CoA: acetyl coenzyme A TCA: tricarboxylic acid aKG: a-ketoglutarate aKGDH: a-ketoglutarate dehydrogenase SCoA: succinyl coenzyme A G1P: glucose-1-phosphate PPa: phosphorylase a PPP: pentose phosphate pathway R5P: ribose-5-phosphate TK: transketolase Ala: alanine ALT: alanine transaminase Asp: aspartate AST: aspartate transaminase OA: oxaloacetate Glu: glutamate Glu  KG can occur in liver using glutamate dehydrogenase aKG SCoA aKGDH vit B1,B2,B3

34 Thiamine pyrophosphate (TPP)
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 alpha- hydroxyketones

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36 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

37 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!

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39 Flavins are one- or two-electron transfer agents
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 Other transfers are possible!

40 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

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42 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+)

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44 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

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46 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.

47 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

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49 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 N- carboxy-biotin The "tether" allows the carboxyl group to be shuttled from the carboxylase subunit to the transcarboxylase subunit of ACC-carboxylase

50 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!

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52 Pyridoxine and pyridoxal phosphate
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

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56 Pyridoxal Phosphate Mechanisms
Figure is a key figure - relate each intermediate to subsequent mechanisms Appreciate the fundamental difference between intermediates 2-5 and 6,7

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58 Vitamin B12 Cyanocobalamin
B12 is converted into two coenzymes in the body: 5'-deoxyadenosylcobalamin methylcobalamin

59 Vitamin B12 Cyanocobalamin
Dorothy Hodgkin determined the crystal structure of B12 in 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 nm (2.05 A) - an essentially covalent bond

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61 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 )

62 FUNGSI BIOKEMIS VITAMIN
B1 (Tiamin) 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

63 FUNGSI BIOKEMIS VITAMIN
As. Panthotenat Merupakan gugus prostetik koenzim A yg mpy fungsi dlm r. acetilasi pada KH, lemak dan metabolisme a.a. Vit. B12 Koenzim sintesa as. Nukleat (RNA), pembentukan gugus methyl pada thyamine 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.

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71 GEJALA DEFISIENSI VITAMIN
Keratinisasi Xeropthalmia D Ricket Osteomalacia E Muscular distropy Exudativediathesis Encephalomalcia K Terhambatnyaproses pembekuan darah

72 GEJALA DEFISIENSI VITAMIN
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 Cobalamin Pertumbuhan yg tidak baik,Anemia, kegagalan fungsi reproduksi

73 KERACUNAN VITAMIN Vitamin Safe Upper Feed Safe Upper Level(unit/kg
Level+ Normal pakan) Level A IU/kg 10 D3 IU/kg >60 d 3-4 IU/kg < 20 d 20-30 E 1000 IU/kg K 2000 mg/kg 1000

74 Terima Kasih