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STRUKTUR, FUNGSI DAN MEKANISMENYA D B1 K E A C B3 B2 B6 B12.

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Presentasi berjudul: "STRUKTUR, FUNGSI DAN MEKANISMENYA D B1 K E A C B3 B2 B6 B12."— Transcript presentasi:

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

2  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  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 PengaruhVitamin yang peka Vitamin yang stabil CahayaVit. A, Karoten, Vit.B1, B2, B6, Vit. C, Vit. D, dan Vit E Choline, as. Pantotenat OksigenVit. A, Karoten, Biotin, Vit.C dan Vit. K Gol. Vit. Bkomplek, as.nicotinat, Vit.D dan Vit. E BasaVit.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) PengaruhVitamin yang peka Vitamin yang stabil AsamVit.A, Karoten, Vit.B2, as.pantotenant, Vit.D Vit. B1,B2,B12, Biotin, Vit.C, Vit.E, dan Vit. K PanasVit.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 Vitamin larut dalam lemak Vitamin larut dalam air Komposisi kimiaC,H,OC,H,O + N,S,Co TerjadinyaJaringan tanaman, ada bentuk provitamin Pada tanaman, tidak ada bentuk provitamin Peran fisiologisKontrol metabolisTransfer energi Absorbsilemakair

8 Perbedaan Vitamin larut dalam lemak dan vitamin larut dalam air Vitamin larut dalam lemak Vitamin larut dalam air PenyimpananDideposit dalam lemak Di seluruh sel hidup EkskresiMelalui fesesTerutama melalui urine. Kadang-kadang ada dalam feses karena ada sintesis oleh mikroba.

9 Perbedaan Vitamin larut dalam lemak dan vitamin larut dalam air Vitamin larut dalam lemak Vitamin larut dalam air Sifat AktivitasA,D,K= Individual E= Broad spectrum Broad spectrum KelainanHypovitaminosis Hypervitaminosis 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 VITAMINSTABILITY CHARACTERISTIC AOxidasi khususnya dengan Fe,Cu D3Oxidasi (kestabilan sedang) EStabil dalam bentuk acetat, sangat tidak stabildalam bentuk alcohol KSangat tidak stabil TiaminSensitif terhadap oxidasi dan pH

13 GENERAL VITAMIN STABILITY VITAMINSTABILITY CHARACTERISTIC Pyridoksin,Kestabilan sedang riboflavin PantotenatSensitif hidrolisis NiasinHampirstabil B12Kestabilan tinggi, beberapa hilang bila kedaluwarsa BiotinHampir stabil AsamfolatKestabilan sedang, sensitif oxidasi dan reduksi Vitamin CSangat tidak stabil dalam bentuk alami

14 VITAMIN LARUT DALAM LEMAK

15 Vitamin A (Retinol) R=CH 2 OH Retinol R=CH 2 OH Retinal R=CH 2 OH Asam Retinoat

16 Vitamin A (Retinol) Retinol

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

18 Fungsi Vitamin A 1.Rangsangan cahaya dari mata ke otak 2.Berperan dalam sel epitel 3.Mengontrol aktivitas tulang

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

20 Defisiensi Vitamin A 1.Buta malam 2.Seroptalamia (pengeringan & iritasi kornea, keruh dan mudah terinfeksi) 3.Terganggu sel

21 Vitamin D D 2 =Ergokalsiferol D 3 =Kholekalsiferol Pro Vit D 2 = ergosterol Pro Vit D 3 = 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 Fungsi Vitamin E 1. Reproduksi 2. Generasi 3. Hati dan Metabolisme 4. Memperbaiki absorpsi Fe 5. Antioksidan

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

26 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 Defisiensi Vitamin K 1. Pembekuan darah terganggu

31 FUNGSI BIOKEMIS VITAMIN VitaminFungsi 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 metabolisme Ca dan P (memperbaiki ossifikasi dan deposisi dalam kartilago dan kulit telur) serta menaikkan aktivitas enzim phytase pd usus tikus Eantioksidan,berperan pada pernafasan jaringan,fosforilsasi dari kreatin fosfat, sintesa as.askorbat dan metabolisme a.a yg mgd belerang KProses pembekuan darah (sintesa prothrombin & bbrp protein plasma), pembentukan RNA

32 VITAMIN LARUT DALAM AIR

33 33 Glycolysis TCA cycle Glycogenolysis a KGDH vit B 1,B 2,B 3 PP a vit B 6 Glc Glycogen G1P R5P TK vit B 1 PDH vit B 1,B 2,B 3 a KG SCoAAcetyl-CoA G6P Pyr G3P ALT vit B 6 Ala AST vit B 6 OA Asp vit B 6 Glu PPP

34 Vitamin B 1 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 B 2  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 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 Coenzyme A Pantothenic acid (vitamin B 3 ) 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 CO 2 or HCO 3 -, 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 CO 2  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 Vitamin B 6 Pyridoxine and pyridoxal phosphate  Catalyzes reactions involving amino acids  Transaminations, decarboxylations, eliminations, racemizations and aldol reactions  See Figure  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 B 12 Cyanocobalamin  B 12 is converted into two coenzymes in the body:  5'-deoxyadenosylcobalamin  methylcobalamin

59 Vitamin B 12 Cyanocobalamin  Dorothy Hodgkin determined the crystal structure of B 12 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 B 12 Function & Mechanism See Figures  B 12 catalyzes 3 kinds of reactions:  Intramolecular rearrangements  Reductions of ribonucleotides to deoxyribonucleotides  Methyl group transfers (assisted by tetrahydrofolate )

62 FUNGSI BIOKEMIS VITAMIN VitaminFungsi Biokemis 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 VitaminFungsi Biokemis 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 CholinePembentukan dan pemeliharaan sel-sel tubuh, sbg methyldonator Vit. CPembentukan 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 VITAMINGEJALA DEFISIENSI AKeratinisasi Xeropthalmia DRicket Osteomalacia EMuscular distropy Exudativediathesis Encephalomalcia KTerhambatnyaproses pembekuan darah

72 GEJALA DEFISIENSI VITAMIN VITAMINGEJALA DEFISIENSITiamin (B1)Anorexsia, polineuritis, nafsu mkn turunRiboflavinCurled toe paralysis, nafsu mkn turun,diareAs.pantotenatPertumbuhan badan & bulu terhenti, Dermatitis (pelupuk mata,sudut mulut,kaki),goose step(babi) NiasinPellagra (dermatitis, diare, dementia), anemia nafsu mkn turun,pertumbuhan terganggu PyridoksinConvulsi (kekejangan), anemia, nafsu mkn turunBiotinPerosis, dermatitisAsam folatAnemia, pertumbuhan terhambat, bulu jelek, depigmentasi, perosis Kholin Hati berlemak, perosis (babi),gangguan pertumbuhan & pembtk kuning telur CobalaminPertumbuhan yg tidak baik,Anemia, kegagalan fungsi reproduksi

73 KERACUNAN VITAMIN VitaminSafe Upper FeedSafe Upper Level(unit/kgLevel+ Normal pakan)Level A IU/kg10 D IU/kg >60 d IU/kg < 20 d20-30 E1000 IU/kg20-30 K2000 mg/kg1000

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