Chapter 10 ( Vitamins ) Flashcards
Biotin ?
1-Coenzyme : biotin-lysine
2-Enzyme and pathway :
pyruvate carboxylase in gluconeogenesis
Acyl CoA carboxylase in fatty acid synthesis
Propionyl CoA carboxylase in odd carbon fatty acids, valine , methionine , isoleucine , thereonine
3- Deficiency : caused by excessive consumption of raw eggs which contain avidin ( biotin binding protein ) also caused by biotinidase deficiency
Symptoms : alopecia , bowel inflammation and muscle pain
Thiamine (B1) ?
1- Coenzyme : thiamine pyrophosphate TPP
2- Enzymes and pathways :
Pyruvate dehydrogenase in PDH
Alpha-ketoglutarate in TCA cycle
Transketolase in HMP shunt
Branched chain ketoacid dehydrogenase in metabolism of valine , leucine , isoleucine
3- Deficiency : caused by alcoholism
Wernic ( ataxia, nystagmus , opthalmoplegia )
Korsakoff ( confabulation , psychosis )
Dry beri beri ( peripheral neuropathy )
Wet beri beri ( high output hart failure , fluid retention , vascular leak )
Niacin (B3) ?
1- Coenzymes : NAD(H) , NADP(H)
2- Enzyme : Dehydrogenases in Many pathways ( oxidation/reduction )
3- Deficiency : Pellagra ( diarrhea , dementia , dermatitis , death )
Folic acid ?
1- Coenzyme : THF
2- Enzymes and pathways ( 1 carbon carrier) :
Thymidylate synthase in thymidine synthesis
Enzymes in purine synthesis
3- Deficiency : caused by alcoholism , pregnancy , hemodialysis
Symptoms : homocystinemia with risk of deep vein thrombosis and atherosclerosis
Megaloblastic anemia
Neural tube defects in fetus if the enzyme was deficient in early pregnancy
Cyanocobalamin (B12) ?
1- Coenzymes : methyl-cobalamin and adenosyl-cobalamin
2-Enzymes and pathways (VOMIT pathway) :
Homocystein methyltransferase in Methionine , SAM
Methymalonyl CoA mutase in odd carbon fatty acids , valine , methionine , isoleucine , threonine
3-Deficiency : causes : pernicious anemia , aging , poor nutrition , bacterial overgrowth of terminal ileum secondary to Crohn disease , chronic pancreatitis , and rarely vegans or infection by D-latum
Symptoms : Megaloblastic anemia
Progressive peripheral neuropathy
Pyridoxin (B6) ?
1- Coenzyme : pyridoxal-P (PLP)
2- Enzymes and pathways (Transamination) :
Aminotransferases such as AST , ALT in protein catabolism
Sigma-Aminolevulinate synthase in heme synthesis
3- Deficiency : caused by Isoniazid therapy
Symptoms : sideroblastic anemia ( ring RBCs ) , cheilosis , stomatitis , convulsions , microcytic hypochromic anemia
Riboflavin ( B2 ) ?
1- Coenzyme : FAD(H2) 2- Enzyme and pathway ( oxidation/reduction): dehydrogenases in many pathways 3-Deficiency : Corneal neovascularization Cheilosis , stomatitis Magenta-colored tongue
Ascorbate (C) ?
1- the only water soluble vitamin which is not made into coenzyme
2- Enzymes and pathways (Antioxidant) :
Prolyl and lysyl hydroxylases in collagen synthesis
Dopamine hyroxylase in catecholamine synthesis
Absorption of iron in GIT
3- Deficiency : caused by diet deficient in citrus fruit and green vegetables
Scurvy : poor wound healing , easy bruising ,bleeding gums , increased bleeding time , painful glossitis , anemia
Pantothenic acid ?
1- Coenzyme : CoA
2- Enzymes and pathways (carrier of fatty acids ) :
Fatty acid synthase and fatty acyl CoA synthetase in fatty acid metabolism
Pyruvate dehydrogenase in PDH
Alpha-ketoglutarate dehydrogenase in TCA cycle
3- Deficiency : rare
Vitamin D ?
1- Function : in hypocalcemia it helps normalize serum calcium level 2- deficiency : cause : Insufficient sun light exposure Inadequate fortified foods End stage renal disease Symptoms : bone demineralization Rickets in children Osteomalacia in adults
Vitamin A ?
1- Function : retinoic acid and retinol act as growth regulators especially in epithelium
Retinal is important in rads and cons for vision
2- Deficiency : caused by fat malabsorption or fat free diet
Symptoms :
Night blindness
Keratinized squamous epithelium
Xerophthalmia ,Bitot spots
Keratomalacia , blindness
Follicular hyperkeratosis
Alopecia
Vitamin K ?
1- Function : gamma-carboxylation of glutamic acid residues in many Ca binding proteins , Factors 2 , 7 , 9 , 10 , protein C , protein S
2- Deficiency : cause :
Fat malabsorption
Prolonged ttt with broad spectrum antibiotics
Breast fed new borns
Infants whose mothers have been treated with certain anticonvulsants during pregnancy such as Phenytoin
Symptoms : prolonged bleeding , easy bruising .
Vitamin E ?
1- Function : antioxidant in the lipid phase , protects membrane lipids from peroxidation 2- Deficiency : caused by fat malabsorption or premature birth Symptoms : Hemolytic anemia Acanthocytosis Peripheral neuropathy Ataxia Retinitis pigmentosum
Hormone form of vitamin D ?
1,25-Dihydroxycholecalciferol / Calcitriol
Causes of renal osteodystrophy ?
End stage renal disease secondary to DM
Fanconi renal syndrome ( renal proximal tubule defect )
Genetic deficiency of 1alpha-hydroxylase ( vitamin D resistant rickets )
