Vitamin B3 - Niacinamide Flashcards
the forms of B3
niacinamide and nicotinic acid (niacin)
B3 is derived from
tryptophan with the help of vit. B6
origin
- plant: legumes, peanut: nicotinic acid
- animal: meat, egg, milk: purine nucleotide
- microbial synthesis
excretion
in urine in the form of nicotinic acid
RU: N-methyl-nicotinic acid
composition of NAD⁺ and NADP⁺
NAD⁺ - niacinamide-ribose-P-P-Ribose-Adenine
NADP⁺ - niacinamide-ribose-P-P- Ribose(-P) -Adenine
degradation of NADP⁺
NADP⁺ -> NAD⁺ -> R-5-P + AMP -> nicotinamide -> nicotinic acid -> urine
which enzymes uses NAD⁺ as cofactor
- glyceraldehyde-3-P dehydrogenase
- lactate dehydrogenase
- isocitrate dehydrogenase
- A-ketoglutarate dehydrogenase
- malate dehydrogenase
- L-glutarate dehydrogenase
- B-OH-butyrate dehydrogenase
- B-OH fatty acyl dehydrogenase
- pyruvate dehydrogenase
NADP⁺ as cofactor; PPP, NADPH+H⁺ production
- glucose-6-P dehydrogenase
- 6-P-gluconate dehydrogenase
- malate enzyme form: pyruvate (non-ru)
- NADP⁺ dep. isocitrate dehydrogenase (cytoplasm, RU)
NADPH+H⁺ as cofactor; NADP⁺ production
Reductases - most important:(from notes)
- 1st and 2nd reductase FA synthesis
- Glutathione reductase
- HMG-CoA reductase (chol. synth)
- ribonucleotide diphosphate reductase (DNA synth)
- glucuronate reductase
- heme oxygenase/biliverdin reductase
- steroid hydroxylase -> synth of bile acid
- epoxy reductase (vit. K)
deficiency: which species are esp. affected
human, dog, poultry
human
pellagra - not enough Trp (make nicotinic acid)
- DDD: diarrhea, dementia, dermatitis
(animals: not dementia, DD)
(incr. melatonin in light skin people - sun make black spots, decr. melatonin in dark skin people - sun make white spots)
dog
black tongue
poultry
poor growth, slipped tendonds, leg disorder
what diey is poor in Trp
zein (protein in corn)
conversion of Trp to nicotinic acid
needs PALP, cat does not have enzyme for this reaction - no deficiency
