NUTR2101 Lecture Notes - Lecture 10: Transcobalamin, Cobalamin, Methylcobalamin
Water Soluble
Vitamin
B9
Folate found in food
(polyglutamate)
Synthetic form as folic acid
(monoglutamate)
B12
Cobalamine
(synthesised by
microorganism mainly
bacteria; plants do not
synthesis Vit B12)
Choline
Vitamin C
Ascorbic acid
Active Form
(Coenzyme)
THFA (convert when
needed?)
Methylcobalamine
5-Deoxyadenosylcobalamin
/
/
Conversion site
GIT (poly to mono glutamate
by folate conjugase) for
absorption
/
/
/
Digestion and
Absorption
folate/polyglutamate need
remove extra glutamates
before being able to absorb,
GIT converts polyglutamate
to mono glutamate
either by active transport or
passive transport when high
dose folic acid is available
It is best absorbed in an
empty stomach
Cobalamin is bound with
protein
R protein produce in mouth
and stomach
R protein transport with food
to stomach
HCL and pepsin free
cobalamin and protein
free cobalamin binds to R
protein and transport to
enterocyte of small intestine
Intrinsic factor produced in
stomach is bind to cobalamin
when R protein and
cobalamin is freed with
pancreatic protease trypsin
Cobalamin is absorbed and IF
degenerate in distal ileum
cobalamin is bound to
transcobalamin II
Can be synthesise in body or
obtained from food;
absorbed in small intestine
with transport proteins
absorption in small intestine
by active transport and
facilitated diffusion
Document Summary
Cobalamine (synthesised by microorganism mainly bacteria; plants do not synthesis vit b12) Git (poly to mono glutamate by folate conjugase) for absorption. Can be synthesise in body or obtained from food; absorbed in small intestine with transport proteins absorption in small intestine by active transport and facilitated diffusion. Absorption folate/polyglutamate need remove extra glutamates before being able to absorb, Git converts polyglutamate to mono glutamate either by active transport or passive transport when high dose folic acid is available. It is best absorbed in an empty stomach. Hcl and pepsin free cobalamin and protein free cobalamin binds to r protein and transport to enterocyte of small intestine. Intrinsic factor produced in stomach is bind to cobalamin when r protein and cobalamin is freed with pancreatic protease trypsin. Cobalamin is absorbed and if degenerate in distal ileum cobalamin is bound to transcobalamin ii.
