Metabolism Flashcards
Vit A / retinol
Vit A—>retinylester—>retinol + FA (carotinase)—> chylomicron —> retinylester (liver).
Storage, transport, metabolism
Metabolism in liver:
Retinylester (retinylester hydrolase) —> retinol (retinol DH)—> retinal (retinal oxidase) —> retinoic acid
Vit D / calciferol
Cholecalciferol, ergocalciferol —> chylomicron —> liver
Storage or activation by microsomes
Activation:
Cholesterol (liver) —> 7-hydrocholesterol —> (uv light) cholecalciferol, D3 (skin) —> (25-hydroxylase) 25-OH cholecalciferol (liver)—> 1-alpha-hydroxylase) 1,25-OH cholecalciferol (kidney)
Vit E / tocopherol
Egg, milk, meat —> chylomicron —> some storage in liver
Storage in liver, AP tissue, in membranes
B5 / pantothenic acid
Liver, egg, grain —> passive transport—> HSCoA (liver)
No storage
B7 / biotin
Liver, egg yolk, grains —> passive transport—> biotin (liver)
No storage
B9 / folic acid
Green vegetables, animal origin diet—> folic acid—> FH2 + FH4= ACTIVE transport—> FH4 (liver)
No storage
B6 / Pyridoxine
Grains, liver, egg —> passive transport—> liver
No storage
In liver:
Pyridoxol—> pyridoxal—> pyridoxic acid
B12 / cobalamine
Liver, fermented diet—>
EF+ R
EF+IF —> TC1 (blood) + TC2 (cells+ blood)
Storage in liver
Vit C / ascorbic acid
Fresh green fruit, vegetables—> active transport (guineapig, human). Passive transport—> glucose (liver) —> ascorbic acid
No storage
NB: birds kidney synth.
B1 / thiamine
Meat, liver, fish, seed coat —>
Thiamine (TTP) —> facilitated diffusion—> thiamine (liver)
In liver:
Thiamine—> thiamine tyrophosphate TPP (thiamine kinase)
Excretion: feces
B2 / riboflavin
Grain, meat, egg, milk —> active transport—> riboflavin (liver)
In liver :
Riboflavin—> FMN —> FAD
No storage
Microbial synth
Vit K/ phylloquinone
Plants (alpha alpha, cabbage )microbes—> phylloquinone—> chylomicron
No storage
Excretion: feces
