Exam 2, thiamin Flashcards
coenzyme for: thiamin
TPP
coenzyme for: riboflavin
FAD, FMN
coenzyme for: niacin
NAD, NADP
coenzyme for: pyridoxine
PLP (pyridoxal 5’ phosphate)
coenzyme for: folate
THF (tetrahydrofolate), it’s the reduced form of folate essential for its activity b/c oxidized form (folic acid) can’t participate in reactions as well
coenzyme for: pantothenic acid
CoA
coenzyme for: biotin
biotin
coenzyme for: B12
B12
main function: thiamin
energy transformation
*thiamin + 2 phosphates -> TPP (participates in decarboxylation of pyruvate) -> 2C acetate + CO2 -> forms ACoA to enter Krebs
what can destroy thiamin*
thiaminase: destroys weak methylene bridge between thiazole and amine group
*found in betel nuts, fermented tea, raw fish, fern leaves, fish paste
*another property of thiamin is that it’s easily destroyed by heat/ oxidation too
RDI thiamin
M: 1.2 mg, F: 1.1 mg
how does thiamin digestion work?
thiamin from animal sources comes in tpp form -> intestinal phosphatases hydrolyze the phosphates (becomes free form) -> absorbed through SI -> portla blood -> liver to active TPP
*plant thaimin is in free form
inhibitors of thiamin
polyhydroxy phenols (tannic/ caffeic acid) , thiaminases, alcohol
what is the relationship between transketolase and thiamin
transketolase is TPP dependent, catalyzes pentose shunt (which is why it’s a good indicator of thiamin status)
what is the 3rd thiamin function (synthesizes ____ through the ___)
synthesis of NADPH (through PPP) -> synthesis of lipids & nucleic acids
what are non-coenzyme roles of thiamin
membrane and nerve conduction (helps maintain a healthy nervous system)
symptoms of thiamin deficiency in nervous system (3 things)
neuritis: inflammation of nerves, paresthesia (irritated nerves, feel like a bug is on you), irritability, mental depression, anorexia
Beri Beri syndrome, its symptoms
disease of the japanese navy & cured by Baron Takaki (more cooked fish and vegetables)
symptoms: unsteady gait, peripheral neuritis, irritability, depression, fear, coma, constipation
in what population has thaimin deficiency been reported*
Karen tribe, border of Thailand-Myanmar where the diet includes betel nuts, fermented tea, raw fish & fish sauce
Christian Eijkman
-THIAMIN
-won noble prize for discovery of vitamins
-noticed that when eating brown rice instead of polished rice, this deficiency decreased
-discovered that thiamin was found in the outer layer of the rice, so if it was processed/ polished -> leads to deficiency
healthy pigeon vs. with beri beri
w/ beri beri: head is retracted (looks like it is biting itself) , after thiamin shot: head perked up, normal
populations at risk for beri beri
alcoholics, low carb diets, low carb diets + tea + raw fish, places where polished rice is a staple
wet beri beri photograph
edematous edema (when you poke the ankle it leaves a mark) also enlarged heart
enlarged heart photograph
wet beri beri