47 terms
Vitamins
B1 (thiamine) - part of what complex?
TPP (thiamine pyrophosphate)
B1 (thiamine) - cofactor for what enzymes?
pyruvate dehydrogenase (glycolysis)
alpha-ketoglutarate dehydrogenase (TCA cycle)
transketolase (HMP shunt)
branched chain AA dehydrogenase
alpha-ketoglutarate dehydrogenase (TCA cycle)
transketolase (HMP shunt)
branched chain AA dehydrogenase
B1 (thiamine) - people you see it with?
alcoholics (secondary to malnutrition and malabsorption) and malnourished
B1 (thiamine) - diseases of deficiency
wernicke-korsakoff syndrome, beriberi (wet and dry)
B2 (riboflavin) - function
cofactor for oxidation and reduction (e.g., FADH2)
B2 (riboflavin) - deficiency
Cheilosis, Corneal vascularization
B3 (niacin) - function
constituent of NAD+,NADP+
B3 (niacin) - derived from what amino acid?
tryptophan
B3 (niacin) - what vitamin is needed for synthesis?
B6 (pyridoxine)
B3 (niacin) - deficiency
Glossitis, Pellagra (Dermatitis, Diarrhea, Dementia)
B3 (niacin) - causes of deficiency
Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and INH (decreased B6)
B3 (niacin) - excess
facial flushing (offset by aspirin)
B5 (pantothenate) - function
part of CoA and fatty acyl synthase
B5 (pantothenate) - deficiency
dermatitis, enteritis, alopecia, adrenal insufficiency
B6 (pyridoxine) - converted into what? why?
pyridoxal phosphate, a cofactor used in transamination (e.g., ALT, AST), decarboxylation reactions, glycogen phosphorylation, and heme synthesis (ALA synthase)
B6 (pyridoxine) - required for synthesis of what vitamin from what amino acid?
niacin from tryptophan
B6 (pyridoxine) - deficiency
convulsions, hyperirritability, peripheral neuropathy
B6 (pyridoxine) - what drugs induce deficiency?
INH and oral contraceptives
B12 (cobalamin) - function
cofactor for homocystein methyltransferase (transfers methyl groups as methylcobalamin) and methylmalonyl-CoA mutase
B12 (cobalamin) - foods found in
animal products
B12 (cobalamin) - can humans make it?
no; only microorganisms
B12 (cobalamin) - size of reserve
very large reserve stored in liver (years worth)
B12 (cobalamin) - causes of deficiency
malabsorption (sprue, enteritis, Diphyllobothrium latum), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), absence of terminal ileum (Crohn's disease), or veganism
B12 (cobalamin) - test for nature of deficiency
Schilling's test
B12 (cobalamin) - what does deficiency do?
macrocytic, megaloblastic anemia; neurologic symptoms (paresthesias, subacute combined degeneration) due to abnormal myelin; irreversible nerve damage if prolonged deficiency
B12 (cobalamin) - sign of deficiency (urine)
methylmalonyl in urine
Folic acid - function
converted to THF, a coenzyme for 1 carbon transfer/methylation reactions; important for synthesis of nitrogenous bases in DNA and RNA
Folic acid - source
Folate is from Foliage
Folic acid - reserve size?
small reserve in liver. must eat green leaves regularly
Folic acid - deficiency
macrocytic, megaloblastic anemia; no neurologic symptoms; MOST COMMON in USA
Folic acid - when is deficiency common?
alcoholism and pregnancy
folic acid - drugs that cause deficiency?
several! (phenytoin, sulfonamides, MTX)
folic acid - why take early in pregnancy
prevent neural tube defects
common sign for folic acid, B12, or B6 deficiency
hyperhomocysteinemia
S-adenosyl-methionine
ATP + methionin = SAM; transfers methyl units; regeneration of SAM is dependent on both B12 and folate
Biotin - function
cofactor for carboxylation enzymes
-pyruvate carboxylase (forms oxaloacetate)
-acetyl-CoA carboxylase (forms malonyl-CoA)
-propionyl-CoA carboxylase (forms methylmalonyl-CoA)
-pyruvate carboxylase (forms oxaloacetate)
-acetyl-CoA carboxylase (forms malonyl-CoA)
-propionyl-CoA carboxylase (forms methylmalonyl-CoA)
Biotin - deficiency
rare. causes dermatitis, alopecia, enteritis.
Biotin - main causes of deficiency
antibiotic use or excessive ingestion of raw eggs (avidin in egg whites binds it)
Vitamin C - function
-antioxidant.
-facilitates iron absorption (keeps it reduced)
-hydroxylates proline and lysine on collagen
-necessary for dopamin beta-hydroxylase which converts dopamine to NE
-facilitates iron absorption (keeps it reduced)
-hydroxylates proline and lysine on collagen
-necessary for dopamin beta-hydroxylase which converts dopamine to NE
Vitamin C - deficiency
swollen gums, bruising, anemia, poor wound healing
Vitamin C - sources
fruits, veggies, limes
Vitamin E - function
antioxidant (protects erythrocytes and membranes from free-radical damage)
Vitamin E - deficiency
fragile erythryocytes (hemolytic anemia), muscle weakness, neurodysfunction
Vitamin K - function
gamma carboxylation of glutamic residues on clotting proteins
Vitamin K - synthesis site
intestines by flora
Zinc - function
zinc fingers. function of 100+ enzymes
Zinc - deficiency
delayed wound healing, hypogonadism, decreased adult hair (axillary, facial, pubic). may predispose to alcoholic cirrhosis