生物化學(xué)-9酶化學(xué)維生素vitamin是維持機(jī)體正常生理功能所必需

ChemistryVitaminandToteachisnottofillavasebuttolighta(vitamin)是維持機(jī)體正常生理功能所必需，功能等方面有著其他物質(zhì)無法替代的作用，是必需維

維生素A視黃醇維生素E(酚)生 維生素維生素

尼克酸 類

PP維生素B6(吡哆醇 維生素B12( 葉酸、泛酸、生物 維生素C抗壞血酸一.維生素A只存在于動物性食物中，包括A1和A2兩種。A12

1

CH3 4

維生素A1(視黃醇2

16

CH334 維生素A2(3-脫氫視黃醇維生素A原(β-胡羅卜素):β胡蘿卜素的15,15’碳原子的位置，通過加氧酶(β-carotene15,15’-deoxygenase)的催化作用，為兩分子的視黃醛。經(jīng)過還原過程，形成β-β-Oxidative

VitaminARetinolform維持上皮組織的正常結(jié)構(gòu)和功能維持正常視覺(明視覺和暗視覺缺乏癥：夜盲癥、干眼①暗視覺中的感光物質(zhì)——視紫紅質(zhì)(桿狀細(xì)胞中視紫紅VA(末端-

醇脫氫

視蛋白+視黃視黃醛(末端-視紫紅質(zhì)中的視黃醛是11-順視黃 71

11-cis-

視蛋（光(視黃醇視蛋（光(視黃醇11-11-順視黃視蛋白（暗Schiff光敏感蛋白—視循

桿狀細(xì)

視紫紅順視黃醛-視蛋異構(gòu)11-順視黃醛＋視蛋 全反視黃醛＋視蛋醇脫氫

醇脫氫11-順視黃（11-順維生素

異構(gòu)

全反視（全反維生素在弱光下看物時，視紫紅質(zhì)中的全反式視黃醛與視蛋白結(jié)合，同時變?yōu)?順視黃醛，引起神經(jīng)沖動，產(chǎn)生視覺。（二）維生素D（又名抗佝僂病維生素，或鈣化醇維生素D

9

7VD3食 膽鈣化醇(維生素D3)羥

25-

7-前維生素維生素肝腎1,25-二羥膽鈣化醇(活性形式25-羥維生素(膽鈣化醇VD2的生成（源自麥角固醇麥角甾麥角甾（麥角鈣化醇兒童佝僂病（三）維生素E族（又名抗不育維生素或酚6-羥苯駢二氫吡喃衍生67675 413579928O1

O

α-3生理功能及缺乏3缺乏維生素E而導(dǎo)致不育。臨用于性和先兆的防治（生素K族（又名凝血維生素）維生素K族有K1、K2、K3、K4。K1,K2是天然存在的。K3,K4是人工合成的。VitaminVitaminOO

(CH2CHCO維生素

O維生素

維生素VitaminKisrequiredforthesynthesisofsomeoftheproteinsinvolvedinbloodcoagulation凝結(jié)Itisacoenzymeforamammaliancarboxylasethatcatalyzestheconversionofspecificglutamateresiduestoγ-carboxyglutamateO---N－CH－C--- |

VitaminK-dependent

---N－CH－C--- |Glutamate γ-Carboxyglutamate肌肉和胃腸道。二、水溶性維生素與輔（一）維生素B1（又名抗腳氣病維生素或硫胺素

N 6 3N

C2

Thiazolium4-甲基-5-

N

2+NC

Thiamine(vitamin

N

2+NC

ThiaminePyruphosphateTPP缺乏癥：WetBeri- ThiamineE1accepts

酸脫羧酶two-

AldehydegrouponTPPisfromandbindsittoTPPforming

transferredbyE1tothelipoamideswingingarmonE2andoxidizedtoanacetylgroup5.Reduced

O

isoxidizedby

Mg2+

Acetyl E3oxidizes

CoA-SHistranferredOreducedlipoamideby hydrogenstoFAD

酵母酸脫羧酶催化機(jī)Mechanismofyeastpyruvate

—

|

+

①ThepositivechargeofthethiazoliumringofTPPattractselectrons,weakeningthebondbetweenC-2andhydrogen.Thisprotonispresumablyremovedbyabasicresidueoftheenzyme.②Ionizationgeneratesaresonance-stabilizeddipolarcarbanionknownasanylid內(nèi)鎓鹽(amoleculewithoppositechargesonadjacentatoms).酵母酸脫羧酶催化機(jī)Mechanismofyeastpyruvate

—

HC－

+

③-1ThenegativelychargedC-2attackstheelectron-deficientcarbonylcarbonofthesubstrate酵母酸脫羧酶催化機(jī)Mechanismofyeastpyruvate |

|

|

|

H

H

③-2 product(CO2)is④Twocarbonsofpyruvatearenowattachedtothethiazoleringaspartofaresonance-stabilizedcarbanion.Inthefollowingstep,protonationofthecarbanion酵母酸脫羧酶催化機(jī)Mechanismofyeastpyruvate

|

⑤

S—

S|

+

CH3-CO-S-⑤HETPPiscleaved,releasingacetaldehyde(thesecondproduct)andregeneratingtheylidformoftheenzyme-TPP⑥TPPre-formswhentheylidisprotonatedbythe（二）維生素PP和尼克酚胺（煙酰胺

5632N5632N Nicotinicacid Pellagra陪拉格病

NAD＋與NADP＋NAD＋：煙酰胺腺嘌呤二核苷酸，輔酶I(Nicotiamideadeninedinucleotide,NAD＋,(Nicotiamideadeninedinucleotidephosphate,NADP＋,

(氧化型O－－－ |

6 N

(還原型O－－－ |

6 N

|O||

N

|

||

N

|

O－－－

O－－－ OH(OPO32-

OH(OPO32-NAD＋與NADP＋乳酸脫氫酶的催化機(jī)Mechanismoflactate|H3C－CH－COO－＋

H3C－C－COO－＋NADH＋ Orderedkineticmechanismforlactatedehydrogenase.Intheforwarddirection,thecoenzymeNAD＋isbound ,anditsreducedform,NADH,isreleasedlast.NAD＋is andNADHreleasedE

EEEE

MechanismoflactateHis-195,abasecatalystintheactivesite, saprotonfromtheC-2hydroxylgroupoflactate,facilitatingtransferofthehydrideion(H－)fromC-2ofthesubstratetoC-4oftheboundNAD＋.Lactatedehydrogenasehasaspecificbindingsiteforthecarboxamidegroup[-C(O)-NH2]ofNAD＋.(Oxidized

H(Reducedsubstrate)

Arg-171formsanionpairwiththecarboxylategroupofthesubstrate.Inthereversereaction,H－istransferredstereospecificallyfromthereducedcoenzyme,NADH,toC-2oftheoxidizedsubstrate,pyruvate.（三）維生素B222N5N1N||Flavinmononucleotide|

Flavinadenine |－O－P－O－ | FMN、FAD作為脫氫酶的輔酶傳遞氫原子是多種氧化還原酶及遞氫體的酶輔基，參與遞氫作用ReductionandoxidationofFMNor ?UnlikeNADHandNADPH,whichparticipateexclusivelyintwo-electrontransfers,FMNH2andFADH2donateelectronseitheroneortwoatatime.?TheconjugateddoublebondsbetweenN-1andN-5arereducedadditionofahydrideionandaprotontoformFMNH2orFADH2,respectively,thehydroquinoneformofeachcoenzyme, 半醌負(fù)離子(紅色氧化(黃色H3C－λmax＝450nm

1 |R

—

NFMNorFAD(quinone++

—

1 |R還原型(無色

1| |HR

FMNH?orFADH?(SemiquinoneApartiallyoxidizedcompound,FADH?orFMNH?,isformedwhenoneelectronisdonated.FMNH2orFADH2(hydroquinoneRiboflavin(B2)------Growth(glossitis舌炎泛酸(VB5):是由-二羥基--二甲基丁酸和一分子-丙氨酸縮合而成。

Pantoate

|N

HS－CH2－CH2－N－C－CH2－CH2－N－C－CH－C－CH2－

丙氨

-二羥基--二甲基丁

2-O3P 2- Pantothenate ADPwith3’-phosphate

-二羥基--二甲基丁丙氨β-巰基乙

HC－ （五）VB6維生素B6又名抗皮炎維生素，即吡哆醇、吡哆醛和吡哆

＋ H

維生素B6的活性形式：磷酸吡哆醛和磷酸吡哆

O ＋

O|

磷酸吡哆

生理功能：是轉(zhuǎn)氨酶和氨基酸脫羧酶的輔酶參與氨基酸代謝磷酸吡哆醛是δ-氨基γ-酮戊酸(ALA)合酶的輔酶,此酶是血紅素合成的限速酶。HEE

| CNE

HCN Substrate

O－+

product

HC

Substrate

Substrate H

CH + +O

|＋

H

product1

product2

－OOC－CH－CH| |O|product2

Substrate

| CNE

EHCN E

+ H

H（六）維生素B12輔維生素B12：是唯一含金屬元素(鈷)的維生素，又稱鈷胺素。維生素 R5,6- (DMB)5,6- 甲基苯并咪 InR咕啉R＝－CH3(in缺乏病Example:Methylmalonyl-CoACoA)tosuccinylCoAbyintramolecularrearrangementsbenzimidazole(DMB)5,6-二甲基苯并咪

↑

StepCleavage

↑O

O

O|

O|

Step

Step

Step Formation

offree

甲基丙二酰-

↑ MegaloblasticAnemia有巨胚紅血球的貧血FolateandVitaminB-Red CellFolateandVitaminB-Red Cellprecursor(stemcell)FolateorVitaminB-12血球的bloodcellsseenhereinthebonemarrowarearrestedatanimmaturestageofdevelopement.Theystillhaveslightlylargerthannormalredblood（七）(pian環(huán)C2中O (CH2)4 Enzyme-boundbiotin.Thecarboxylategroupofbiotiniscovalentlyboundviaamidelinkagetotheε-aminogroupofalysineresidue(blue).ThereactivecenterofthebiotinmoietyisN-1(red). HCO－＋ATP＋acetyl-CoAADP＋P＋malonyl-CoA 酶A

O ADPO ADP+ SCOO SCN

Enol

|O O SC

（八）葉酸和四氫葉酸(FH4或

FolicAcidorTetrahydrofolic2-氨基-4-羥基-6-甲基-喋呤對氨基苯甲 23N23N

23N23N

HNNHNN

5-

OxidationN N

缺乏?。?/p>

O

NNHNN

HH

N N H

亞甲

O