Biochemistry-Nutrition Flashcards
thiamine
B1, TPP
riboflavin
B2, FAD, FMN
niacin
B3, NAD+
pantothenic acid
B5, CoA
pyridoxine
B6, PLP
biotin
B7
folate
B9
cobalamin
B12
ascorbic acid
VitC
Vitamin A
differentiation of epithelial cells; prevents squamous metaplasia; used to treat measles, AML (M3)
Vitamin A deficiency
night blindness, dry/scaly skin, alopecia, corneal degeneration, immune supression
Vit A toxicity
arthralgias, scaly skin, cerebral edema, osteoporosis; teratogenic so need pregnancy test before starting isotretinoin for severe acne
TPP is a cofactor for which reactions?
ATP: alpha-ketoglutarate dehydrogenase (TCA cycle); transketolase (HPM shunt in RBCs); pyruvate dehydrogenase (links glycolysis to TCA cycle; pyruvate to acetyl CoA); branched chain ketoacid dehydrogenase
confusion, opthalmoplegia, ataxia + confabulation, etc
Wernicke Korsakoff syndrome–damage to medial dorsal nucleus of thalamus, mamillary bodies; make diagnosis by increased RBC transketolase activity after thiamine
poylneuritis, synmmetrical muscle wasting
dry beriberi (thiamine deficiency)
high output cardiac failure (dilated cardiomypathy); edema
wet beriberi (thiamine deficiency)
B1 deficiency
impaired glucose breakdown, ATP depletion worsened by glucose infusion, if suspect, always give B1 first!
What reaction in citric acid cycle uses vitamin B2?
B2–>riboflavin–>FAD/FMN–>succinate dehydrogenase (makes 2 ATP)
B2 deficiency:
cheilosis, corneal vascularization
What vitamins are needed to make B3?
B3 is niacin. tryptophan is precursor. Niacin synthesis requires B2 and B6.
What causes B3 deficiency? Symptoms
Hartnup disease (decreased tryptophan absorption); malignant carcinoid (increased tryptophan use); isoniazid (decreased B6); Diarrhea, dementia, dermatitis
Niacin overdose?
facial flushing (prostaglandin mediated) hyperglycemia, hyperuricemia
Vitamin B5 deficiency
dermatitis, enteritis, alopecia, adrenal insufficiency
What is B6 used for
converted to pyridoxal phosphate, cofactor used in transamination, decarboxylation reactions, glycogen phosphorylase, synthesis of cystathione, heme, niacin, histamine, and neurotransmitters (serotonin, epinephrine, norepinephrine, dopamine, GABA)
B6 deficiency?
convulsions, hyperirratibility, peripheral neuropathy, sideroblastic anemias (impared hemeoglobin synthesis and iron excess)
B7 is used for:
composes biotin, cofactor for carboxylation enzymes
eating too many egg whites
B7 deficiency (avidin binds biotin)
Use of B9?
converted to tetrahydrofolate (THF); 1-carbon transfer/methylation rxns; synthesis of nitrogenous bases
What distinguishes B9 from B12 deficiency?
B12 has neurological symptoms, increased methymalonic acid levels
Vitamin C
facilitates iron absorption by reducing it to Fe2+ states; necessary for hydroxylation of proline/lysine in collagen snthesis; necessary for dopamine B-hydroxylase to convert dopamine to NE
hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination
Vit E deficiency–can appear similar to B12, but does not have megaloblastic anemia, hypersegmented neutrophils, or increased serum MMA levels
