* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download B vitamins
Survey
Document related concepts
Metalloprotein wikipedia , lookup
Point mutation wikipedia , lookup
Peptide synthesis wikipedia , lookup
Plant nutrition wikipedia , lookup
Proteolysis wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Genetic code wikipedia , lookup
Butyric acid wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Citric acid cycle wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Biosynthesis wikipedia , lookup
Nicotinamide adenine dinucleotide wikipedia , lookup
Transcript
PHM142 Fall 2016 Instructor: Dr. Jeffrey Henderson Vitamin B October 4th, 2016 Presentation by: Vicky Wong, Tiffany Wu, Selina Pang, Hiu Yan Fiona Ho What is Vitamin B (B Complex)? • Water soluble vitamins • Need continuous daily supply • Play crucial role in cell metabolism • Form part of coenzymes that help enzymes release energy from foods • Found in grains, meat, poultry, eggs, fish, milk, vegetables • Vitamin B1, B2, B3, B5, B6, B7, B9, B12 Vitamin B1 (Thiamine) • Whole-grain, enriched grain products, pork • Increase need with increasing body weight and metabolism • No toxicity observed • Synthesize coenzyme thiamine pyrophosphate (TPP) • Deficiency causes a disease called beriberi Thiamine Pyrophosphate (TPP) • Coenzyme • Synthesized from thiamine using ATP • Reactive group: thiazolium ring • Pyruvate decarboxylase • • Catalyzes reaction for alcohol fermentation Pyruvate dehydrogenase • Complex converts pyruvate to acetyl CoA for Krebs cycle B1 Deficiency (Beriberi) • • • “Dry” symptoms • Damage to nervous system • Ex. Weakness in legs, atrophy of muscles and skin “Wet” symptoms • Damage to cardiovascular system • Ex. increased blood pressure, edema, enlarged heart Other symptoms • Anorexia, nausea Causes of B1 Deficiency • • • Infections or increasing physical exertion • Fever • Pregnancy Alcoholism • Impairs B1 absorption and enhances excretion • Wernicke-Korsakoff syndrome (brain damage) Gastrointestinal disturbances • Vomiting, gastric bypass Vitamin B2 (Riboflavin) • Precursor of two important coenzymes, Flavin Adenine Dinucleotide (FAD) and Flavin Mononucleotide (FMN) • They have several functions: • • • Electron carriers → important in metabolic pathways involving carbohydrates, fats, and proteins Antioxidant Involved in the metabolism of other B vitamins (such as B3 and B6) Ex. Role of FAD and FMN in Krebs Cycle & ETC Ex. Antioxidant Effects of Riboflavin Vitamin B2 (Riboflavin) • Dietary source: dairy products, dark green vegetables, whole grain, meat • Deficiency symptoms: sore throat, inflammation of tongue, lesions of the skin • Deficiency may impair iron absorption and hemoglobin synthesis • No known toxicity Vitamin B3 (Niacin / Nicotinic Acid) • Dietary Sources: meat, fish, and grain products • Deficiency: severe deficiency causes pellagra • Toxicity: high doses of niacin can be toxic Vitamin B3 (Niacin / Nicotinic Acid) • Derivative: Nicotinamide • Precursors of the coenzymes: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) NAD & NADP • Redox Reactions: • Accept or donate electrons • NAD • • Degrade carbohydrates, fats, proteins and alcohol NADP • Synthesize fatty acids, cholesterol • Non-Redox Reactions: • NAD • Separate the Nicotinamide moiety from NAD • Transfer ADP-ribose to acceptors. NAD & NADP Metabolic Pathway Vitamin B3 Deficiency • Symptoms of Mild Deficiency: • Indigestion, fatigue, canker sores, vomiting, poor circulation, depression • Symptoms of Severe Deficiency: Pellagra • Characterized by the 4 D's: • Dermatitis • Diarrhea • Dementia • Death Vitamin B5 (Pantothenic acid) • In beef, poultry, whole grains, potatoes, tomatoes, and broccoli • Deficiency rare • Symptoms: failure of body systems, fatigue, neurological disturbances etc. • No toxic effects observed • Most exist as CoA or acyl carrier protein (ACP) Coenzyme A (CoA) • Synthesized from vitamin B5 • Carrier of acetyl and other acyl groups • Ex. Acetyl CoA used in Krebs cycle • Energy metabolism • Oxidation of fatty acids • Lipid metabolism CoA Synthesis from Pantothenic Acid Other Possible Functions • Skin moisturization • Improve symptoms of rheumatoid arthritis • Pantotheine (derivative of pantothenate) can help reduce fats for high cholesterol people • Helps body use riboflavin (vitamin B2) Side Note: • Destroyed by canning, freezing, and refining processes Vitamin B6 • Sources: pork, meats, whole grains and cereals, fruits, vegetables • Deficiency symptoms: • Skin disorders, cracks at corners of mouth, anemia, kidney stones, nausea, mental confusion in infants • Toxicity symptoms: • Neurological damage Vitamin B6 • 3 forms - pyridoxal, pyridoxine, pyridoxamine • Active coenzyme form is pyridoxal-5-phosphate, PLP (two tautomeric forms) Pyridoxal-5-Phosphate (PLP) ● Transfer amino groups -NH2from amino acids to keto acids ● Involved in 100+ reactions, mainly in amino acid and neurotransmitter metabolism ○ Transaminations, α- and β-decarboxylations, β- and γ-eliminations, racemizations, aldol reactions ○ Protein and urea metabolism ○ Conversion from tryptophan to niacin or to serotonin ○ Synthesis of heme, insulin, nucleic acids, lecithin (phospholipid) 7 Classes of Reactions Catalyzed by PLP Chemistry of PLP • Versatile • Reacts with amino groups on amino acids to form stable Schiff base (aldimine) adducts • Stabilizes reaction intermediates by acting as an electron sink Vitamin B9 (Folate/Folic Acid) • Folate is the natural form, folic acid is the synthetic form • Dietary source: lentils, beans, dark green vegetables • In Canada, folic acid is added into white flour to reduce the risk of neural tube defects Vitamin B9 (Folate/Folic Acid) • Primary coenzyme form is THF (tetrahydrofolate) • Methyl donor in many reactions • Functions: • • Synthesizing DNA and RNA Converts vitamin B12 to coenzyme form EX. THF in conversion of dUMP to dTMP Folate Deficiency • Low levels of folate in early pregnancy may cause neural tube defects in the fetus • Brain and spinal cord • Open or closed defect • Anencephaly, spina bifida, early death, etc. • Deficiency in folate may lead to anemia • Need folate to make RBC Summary • B Vitamins are water soluble and play a crucial role in cell metabolisms as they form part of coenzymes that help enzymes release energy from foods. • Vitamin B1 (Thiamine) synthesizes coenzyme thiamine pyrophosphate (TPP), with an active thiazolium ring, which enables the enzyme pyruvate dehydrogenase to convert pyruvate to acetyl-CoA in the Krebs cycle. Thiamine deficiency causes a disease called beriberi, which has “wet” (cardiovascular) and “dry” (nervous system) symptoms. • Vitamin B2 (riboflavin) forms two coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes are involved in energy metabolism (carbohydrate, fat, protein) as electron carriers. They also have antioxidant effects through FAD-dependent glutathione reductase. • Vitamin B3 (Niacin) is the precursor of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). Niacin coenzymes degrade carbohydrates, fats, proteins and alcohols and synthesize fatty acids and cholesterol. They play a role in cell signaling and DNA repair. • Vitamin B5 (Pantothenic acid) is part of the chemical structure for coenzyme A (CoA), which is a carrier of acetyl and acyl groups used in many metabolic pathways including the Krebs cycle. • Vitamin B6’s active form is pyridoxal-5-phosphate (PLP), which is very versatile and participates in many reactions, mainly in amino acid and neurotransmitter metabolism. • Vitamin B9 (folic acid/folate) is a precursor for tetrahydrofolate (THF), which is an important methyl donor in many reactions. THF is involved in DNA and RNA synthesis so it is crucial to rapidly dividing cells. Deficiency in folate can cause anemia (there will be large but few RBC) and neural tube defect in developing fetus. References Bates, C. J. (2004, June 17). Pantothenic Acid. Encyclopedia of Human Nutrition. doi:10.1016/B0-12-226694-3/00247-7 Bellows, L, & Moore, R. (2012, November). Water-Soluble Vitamins: B-Complex and Vitamin C. Retrieved from: http://extension.colostate.edu/docs/pubs/foodnut/09312.pdf Brown, G. M. (1958, September 15). The mechanism of pantothenic acid. The Journal Of Biological Chemistry, 234(2). Cowgill, G. R. (1938, September 10). HUMAN REQUIREMENTS FOR VITAMIN B1. The Journal of American Medical Association, 11(111), 1009-1016. doi:10.1001/jama.1938.72790370004008 Ehrlich, S. D. (2013, July 16). Vitamin B5 (Pantothenic acid). Retrieved from http://umm.edu/health/medical/altmed/supplement/vitamin-b5-pantothenic-acid Ehrlich, S. D. (2015, June 8). Vitamin B3 (Niacin). Retrieved from http://umm.edu/health/medical/altmed/supplement/vitamin-b3-niacin Garrett, R. H., et al. (2013). Biochemistry: First Canadian Edition. Toronto: Nelson Education Ltd. Garrett, R. H., Grisham, C. M. Biochemistry: Fifth Edition. Boston: Brooks Cole. Higdon, J. (2000). Niacin. Retrieved from http://lpi.oregonstate.edu/mic/vitamins/niacin Leonardi, R., Zhang, Y., Rock, C. O., & Jackowski, S. (2005, March/April). Coenzyme A: Back in action. Progress in Lipid Research, 44(2-3), 125-153. doi:10.1016/j.plipres.2005.04.001 Liou, B. S. (n.d.). Riboflavin. Retrieved September 28, 2016, from http://web.stanford.edu/group/hopes/cgi-bin/hopes_test/riboflavin/ Powers, H. J. (2003). Riboflavin (vitamin B-2) and health. The American journal of clinical nutrition, 77(6), 1352-1360. Riboflavin. (2016). Retrieved September 25, 2016, from http://lpi.oregonstate.edu/mic/vitamins/riboflavin Strauss, M. B. (1938, March 26). THE THERAPEUTIC USE OF VITAMIN B, IN POLYNEURITIS AND CARDIOVASCULAR CONDITIONS. The Journal of American Medical Association, 110(13), 953-956. doi:10.1001/jama.1938.62790130003006 Vitamin B9 (Folic acid). (n.d.). Retrieved September 26, 2016, from http://umm.edu/health/medical/altmed/supplement/vitamin-b9-folic-acid Voet, D., Voet, J., & Pratt, C. (2013). Fundamentals of Biochemistry Life at a Molecular Level (4th ed.). John Wiley & Sons. Whitney, E., & Rolfes, S. R. (2013). Understanding Nutrition (13th ed.). Belmont, CA: Wadsworth.