B12 and choline Flashcards
natural form of B12
cobalamin
synthetic form of B12
cyanocobalamin
coenzyme in propionyl CoA–>succinyl CoA
5’-deoxyadenosylcobalamin
R=___ which is a protein that protects B12 from HCl and pepsin
haptocorrins
haptocorrins are found in ____
saliva and gastric juice
Ileum has ____ receptor
B12-IF
IF-B12 complex can be absorbed by ___ process called ____ which is __% efficient
active; endocytosis; 50
if no IF, only ___ absorption of about __% possible
passive; 1
B12 is transported in plasma attached to ____
transcobalamin II
what is unusual about B12 that makes it diff from other B vitamins?
stored in liver (which is secreted in bile)
hyperhomocysteinemia contributes to:
heart disease, poor cognition, cancer
unique symptom of B12 deficiency
neuropathy (nerve damage)
no IF is known as _____ anemia
pernicious (can’t absorb B12 properly)
neuropathy may be associated with build up of ___
methylmalonic acid (MMA)
reasons for secondary deficiency for B12
1) low stomach acid 2) pancreatic insufficiency
3) ileum resection 4) No IF
tests of status for B12 deficiency unique to B12?
v serum B12, ^MMA
food sources of B12?
microbial synth (meat, eggs, dairy), contaminated soil/water with manure (inadvertent), our own large intestine (but we can’t use)
absorption efficiency of B12?
50%
turnover of B12 about ____mcg/day
1
B12 can be given as _____ strips
sub-lingual
choline important for metabol of _____
methyl groups
choline is converted to ___ to be methyl donor (form in liver)
betaine
dietary choline found in foods as ____ choline, also called ____
phosphatidyl choline; lecithin
AI for choline set to prevent ___
liver damage
in deficiency of choline, see rise in _____ in blood
alanine aminotransferase
supplemental form of choline:
choline chloride
choline has ___ charge and ____ methyl groups
positive; 3
choline made from de novo synth from ____
serine
betaine is also called ___
trimethylglycine (TMG)
betaines found in ___
beets
can make phosphatidyl choline from ____
phosphatidyl ethanolamine
basis for setting UL?
prevent hypotension, fishy body odor, nausea
