Exam 2, thiamin

Question 1

coenzyme for: thiamin

Answer 1

TPP

Question 2

coenzyme for: riboflavin

Answer 2

FAD, FMN

Question 3

coenzyme for: niacin

Answer 3

NAD, NADP

Question 4

coenzyme for: pyridoxine

Answer 4

PLP (pyridoxal 5’ phosphate)

Question 5

coenzyme for: folate

Answer 5

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

Question 6

coenzyme for: pantothenic acid

Answer 6

CoA

Question 7

coenzyme for: biotin

Answer 7

biotin

Question 8

coenzyme for: B12

Answer 8

B12

Question 9

main function: thiamin

Answer 9

energy transformation
*thiamin + 2 phosphates -> TPP (participates in decarboxylation of pyruvate) -> 2C acetate + CO2 -> forms ACoA to enter Krebs

Question 10

what can destroy thiamin*

Answer 10

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

Question 11

RDI thiamin

Answer 11

M: 1.2 mg, F: 1.1 mg

Question 12

how does thiamin digestion work?

Answer 12

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

Question 13

inhibitors of thiamin

Answer 13

polyhydroxy phenols (tannic/ caffeic acid) , thiaminases, alcohol

Question 14

what is the relationship between transketolase and thiamin

Answer 14

transketolase is TPP dependent, catalyzes pentose shunt (which is why it’s a good indicator of thiamin status)

Question 15

what is the 3rd thiamin function (synthesizes ____ through the ___)

Answer 15

synthesis of NADPH (through PPP) -> synthesis of lipids & nucleic acids

Question 16

what are non-coenzyme roles of thiamin

Answer 16

membrane and nerve conduction (helps maintain a healthy nervous system)

Question 17

symptoms of thiamin deficiency in nervous system (3 things)

Answer 17

neuritis: inflammation of nerves, paresthesia (irritated nerves, feel like a bug is on you), irritability, mental depression, anorexia

Question 18

Beri Beri syndrome, its symptoms

Answer 18

disease of the japanese navy & cured by Baron Takaki (more cooked fish and vegetables)
symptoms: unsteady gait, peripheral neuritis, irritability, depression, fear, coma, constipation

Question 19

in what population has thaimin deficiency been reported*

Answer 19

Karen tribe, border of Thailand-Myanmar where the diet includes betel nuts, fermented tea, raw fish & fish sauce

Question 20

Christian Eijkman

Answer 20

-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

Question 21

healthy pigeon vs. with beri beri

Answer 21

w/ beri beri: head is retracted (looks like it is biting itself) , after thiamin shot: head perked up, normal

Question 22

populations at risk for beri beri

Answer 22

alcoholics, low carb diets, low carb diets + tea + raw fish, places where polished rice is a staple

Question 23

wet beri beri photograph

Answer 23

edematous edema (when you poke the ankle it leaves a mark) also enlarged heart

Question 24

enlarged heart photograph

Answer 24

wet beri beri

Question 25

dry beri beri photograph

Answer 25

muscle wasting, foot and toe drop (drags while walking bc nerve damage), frail and weak lower body, thin limbs bc muscle deterioration

Question 26

irritable rat photograph: name of condition + what deficiency?

Answer 26

Wernicke-Korsakoff syndrome, goes away when you give a shot of vitamin B1 (thiamin)

Question 27

Which syndrome related to vitamins might an alcoholic develop? What is the disease and what are the resulting health consequences?*

Answer 27

Wernicke-Korsakoff
-thiamin deficiency syndrome, related to alcoholism and/ or malnutrition (not enough thiamin or impaired utilization)
-* impairs phosphorylation of thiamin and TDP action *
-decreased thaimin absorption
-results in: malnutrition, decreased liver function, if chronic could lead to psychosis

Question 28

toxicity of thiamin

Answer 28

-none seen with 500mg-1g/ day
-would have to be very large amounts through IV
-no tolerable INTAKE level from food, water soluble so excreted if necessary

Question 29

riboflavin coenzymes & what do they do

Answer 29

FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide)
-accept and transfer H ions

Question 29

main thiamin food source*

Answer 29

pork