Chapter 4 Vitamins

Classification of vitamins vitamins water -soluble lipid-soluble Vit C Vit B A, D, E, K B1, B2, B6, B12, PP, pantothenic acid ， folic acid,biotin,lipoic acid

Section 2 Water-soluble vitamins

Common features: ﹡ water soluble ， easy to be discharged through urine ﹡ not easy to be stored in the body ， requiring diet inception Classification: Vitamin B family Vitamin C

Chemical nature and properties: ﹡ vitamin B 1 : thiamine ﹡ active form :Thiamine pyrophosphate (TPP) 1. Vitamin B1 (thiamine )

Thiamine pyrophosphate (TPP) Chemical structure of vitamin B1

biochemical function: ﹡ TPP: co-enzyme of oxidative decarboxylation of α–keto acids and transketolase ﹡ with effects in the nerve conduction ， inhibiting the cholinesterase activity Deficiency: ﹡ beriberi ， peripheral Neuritis Biochemical functions and deficiency

Components of Pyruvate Dehydrogenase complex enzyme E 1 ： Pyruvate Dehydrogenase E 2 ： Dehydrolipoyl Transacetylase E 3 ： Dehydrolipoyl Dehydrogenase HSCoA NAD + co-enzyme TPP Lipoic acid （ ) HSCoA FAD, NAD + S S L pyruvate acetyl CoA NAD +, HSCoA CO 2, NADH + H + Pyruvate Dehydrogenase complex

2. Vitamin B2 (riboflavin) Chemical nature and properties: ﹡ vitamin B 2 : riboflavin ﹡ active form : flavin mononucleotide (FMN) flavin adenine dinucleotide (FAD)

Vit B 2 FMNAMP FAD Ⅰ ⅡⅢ Chemical structure of FMN and FAD

Hydrogen transmission of FMN and FAD Succinate fumarate Succinate dehydrogenase

biochemical function ： FMN and FAD are the prosthetic group of oxidoreductases with function of transmitting hydrogen deficiency ： cheilosis ， glossitis, scrotitis etc. Biochemical functions and deficiency

3. Vitamin PP (Niacin) Chemical nature and properties: ﹡ vitamin PP: nicotinic acid nicotinamide ﹡ active form: Nicotinamide adenine dinucleotide (NAD + ) Nicotinamide adenine dinucleotide phosphate (NADP + )

Chemical structure of nicotinic acid and nicotinamide

Chemical structure of NAD and NADP

biochemical function: ﹡ NAD + and NADP + : coenzyme of dehydrogenases （ Malate dehydrogenase, lactate dehydrogenase), transfer of hydrogen 。 deficiency ﹡ pellagra Biochemical functions and deficiency

4. Vitamin B 6 Chemical nature and properties : ﹡ vitamin B 6 : pyridoxine pyridoxal pyridoxamine ﹡ active form : pyridoxal-phosphate pyridoxamine-phosphate

Chemical structure of Vitamin B 6

Transamination reaction

Biochemical functions and deficiency biochemical function: ﹡ Pyridoxal-Phosphate: Coenzyme of amino acid aminotransferase, decarboxyIase, and  - amino-  - levulinate synthase （ ALA synthase ） deficiency ﹡ nervousness, anemia, etc.

5. Pantothenic acid Chemical nature and properties : ﹡ pantothenic acid ﹡ active form : CoA ACP (acyl carrier protein) biochemical function and deficiency ﹡ CoA and ACP are coenzymes of acyl transferase ， transfer of acyl

Pantonic acid

6. Biotin Biochemocal function: Biotin: co-enzyme of carboxylase （ eg. pyruvate carboxylase ） Binding to ε- amino residue of lysine to form biocytin Binding to carboxyl to form carboxyl biotin

7. Folic acid (Folacin) Chemical nature and properties: ﹡ folic acid: pteroylglutamic acid ﹡ active form: tetrahydrofolate (FH 4 )

Folic acid FH2 reductase NADPH+H + NADP + FH 2 FH2 reductase NADPH+H + NADP + FH 4 5, 6, 7, 8-FH 4

biochemical function ： FH 4 : co-enzyme of transferase of one carbon unit deficiency : megaloblastic anemia clinical application: antitumor drug Biochemical functions and deficiency

8. Vitamin B 12 (cobalamine) Chemical nature and properties : vitamin B 12 : cobalamine active form: methylcobalamine 5 -deoxyadenosylcobalamin

R ： -CH 3 methylcobalamine R ： 5`-deoxyadenosine 5`- deoxyadenosylcobalamin Chemical structure of Vitamin B 12

﹡ biochemical function ： methyl transfer ﹡ deficiency ： megaloblastic anemia, nerve disease, high blood level of homocysteine Biochemical functions and deficiency

8. Vitamin C (ascorbic acid) Chemical nature and properties: structure: Vitamin C Dehydro-vitaminC

﹡ biochemical function ： redox reaction, hydroxylation, synthesis of collagen protein ， absorbance of ferralia ﹡ deficiency ： scurvy Biochemical functions and deficiency

9. Lipoic acid Oxidize type Reduce type

Cooperating with TPP to participate oxidative decarboxylation of pyruvic acid 、 α- keto acid as coenzyme of lipoic acid acetyl transferase. Biochemical functions and deficiency

水溶性维生素 （大多数 B 族维生素的衍生物是结合蛋白酶的辅酶） 维生素活性形式主要功能缺乏症 VitB 1 （硫胺素） 焦磷酸硫胺素 (TPP)α- 酮酸氧化脱羧酶的辅酶脚气病， 末梢神经炎 VitB 2 （核黄素） 黄素单核苷酸 (FMN) ， 黄素腺嘌呤二核苷酸 (FAD) 体内氧化还原酶的辅酶，递氢口角炎， 舌炎等 VitB 6 磷酸吡哆醛， 磷酸吡哆胺 体内氨基酸转氨酶及脱羧酶的辅酶； ALA 合酶的辅酶 人类未发现 缺乏症 VitB 12 （钴胺素） 甲基钴胺素， 5’- 脱氧腺苷钴胺素 甲基转移酶的辅酶巨幼红细胞 贫血 VitPP 尼克酰胺腺嘌呤二核苷酸 (NAD + ) ，尼克酰胺腺嘌 呤二核苷酸磷酸 (NADP) 体内多种脱氢酶的辅酶，递氢赖皮病 泛酸 CoA ， 酰基载体蛋白 (ACP) 酰基转移酶的辅酶人类未发现 缺乏症 叶酸 四氢叶酸（ FH 4 ）一碳单位转移酶的辅酶巨幼红细胞 贫血 生物素 羧化酶的辅酶很少缺乏 硫辛酸 硫辛酸乙酰转移酶的辅酶 VitC （ L- 抗 坏血酸） 抗氧化剂；促进铁的吸收；参与羟化反应坏血病