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98 Cards in this Set

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What are the enzymatic cofactors?
1. Thiamin
2. Pyroxdial
3. Mangenese
4. Robiflavin
5. Pantothenic acid
6. Magnesium
7. Niacin
8. Lipoic Acid
9. Zinc
10. Biotin
11. Vitamin K
12. Copper
What two cofactors are needed for electron transfer?
niacin and riboflavin
what cofactor is needed for transaminations?
b6
What cofactor is needed for acod/aldehyde tranfers?
thaimin
What cofactor is needed for Thio-ester transfers?
Pantothenic acid- part of coenzyme A
What cofactor is needed for decarboxylations?
lipoic acid, b6, thiamin
What cofactor is needed for carboxylations?
biotin
What cofactor is needed for one-carbon transfers?
b12 and folate
what micronutrients are used for one-carbon usage?
b12, folate, cobalt
What are the antioxidants?
Vit E & C, B-carotene, selenium copper
What are the micronutrients that are hormones?
Vit A & D, iodine for thyroid hormone
What are the micronutrients that are used bone formation?
calcium, phosphate, magnesium, Vit D, Fluoride
What are the micronutrients that are used in vascular homeostasis?
sodium, potassium, chloride
What are the micronutrients that for cardiovascular function?
antioxidants, iron, chromium, magnesium, silicon
Thiamin is what vitamin?
B1
What is vitamin used as a cofactor for?
1. Transfer of carboxyl and aldehyde groups in CHO and branched chained amino acid metabolism- decarboxylation & transketolation

2. Neurotransmission and nerve conduction
What two enzymes does thiamin help to decarboxylate?
1. Pyruvate DH
2. Alpha KG DH
What is transketolation? And how is thiamin involved?
It is the transfer of aldehyde b/n sugars in the pentose phosphate pathway
what is thiamin's role in neurotransmission and nerve conduction?
Thiamin affects the level of neurotransmittors (acetylcholine, catecholamines, norepinephren, serotonin) and it's effects are independent of coenzyme function
Does TPP accept or donate electrons?
BOTH
What is the active thiamin metabolite?
TPP, TDP- thiamin pyrophosphate
where is thiamin pyrophosphate made in the body?
made in the liver/brain by thiamin pyrophosphokinase

thiamin+ ATP-> Thiamin-P-P + AMP
what does the enzyme TPP-ATP phosphoryl transferase do?
TPP->TTP
what does the enzyme thiamin pyrophosphatase?
TPP-> TMP
What is the organ distribution of thiamin?
Low in Brain (high fat, lower water in the brain)

High in skeletal muscle (50%), heart, liver, kidney
What is the intracellular distribution of thiamin?
Nuclear, Mitos (significant amount), cytosol

Mitos- energy metabolism (pyruvate DH and alpha KGDH
What are the three TPP-mediated reactions?
1. Pentose Phosphate pathway
2. Pyruvate DH
3. Alpha KG DH
What is the characteristics of dry beri-beri?
Paralytic or nervous beri-beri (thiamin deficiency)

Peripheral neuropathy, memory loss, tingling, numbness, weakness
What is the characteristics of wet beri-beri?
Cardiovascular problems: enlarged heart, edema, condition worsened by exercise, high CHO diet (stress TCA cycle and glycolysis)
What are the characteristics of cerebral beri-beri?
Wernicke-korsakoffs syndrome:encephalopathy

occurs in alcoholics- low intake of water-soluble and impaired of intestinal absorption

malnutrition, POW(high milled rice and low meat diet)

confusion, amnesia, cause of dementia
What is the characteristics of marginal deficiency of Vitamin B1?
A subclinical deficiency is common in the US (17-20%) which means they have a <70% of the RDA
Who is at risk for the thiamin deficiency?
elderly, children, teens, stress, alcoholics, athletes
when is thiamin deficiency diagnosed?
autopsy
What are the thermolabile antagonists for thiamin?
These compounds are destroyed by heat and are thaiminases I and II that degrade thiamin. They are abundant in raw fish and shellfish (sushi?), cabbage, brussel sprouts and microbs
What are the thermostable thiamin antagonists?
These compounds cannot be destroyed by heat. They are tannins, caffeic acid (tea, cofffee). These tannins and polyphenolics bind and activate thiamin. Calcium and magnesium increase precipitation of thiamin by tannin and make it less bioavailable.
What do ruminants have to do with thiamin deficiency?
Thiaminase activity of bacteria and some ruminant bacteria can also supply bacteria
What are the two analogs that can induce thiamin deficiency?
1. oxythiamin chloride: add PP (pyrophosphate) to it and competes with TPP

2. Pyrithiamin: prevents the formation TPP
What is leigh's syndrome?
is related to thiamin and it is a subacute neuron problem- TTP may enhance brain viability
Thiamin-responsive megaloblastic anemia is the mechanism known?
unknown mech
What is thiamin-responsive lactic acidosis?
increase pyr DH activity and removes lactate
what is maple syrup urine disease?
defective debranching chain ketoacid DH
What is the requirement for thiamin?
.5 mg/ 1000 kcal
.8 mg/ 1000 kcal- preggy or lactation
1.0 mg /1000 kcal- eldery
what are the good dietary sources of thiamin?
yeast, lean pork, legumes, grains, pastas, rice are rich sources
what are poor dietary sources of thiamin?
milk products, seafoods, fruits and vegetables
what are some other ways to destroy thiamin?
Thiamin is unstable above pH 8 (like if you add sodium barcarbonate), it is destroyed by heat, cooking water, and radiation

NOT by freezing
What is the absorption route of thiamin?
It is actively abs in the jejunum and ileum (<2um) and its passively diffusion if smaller than 2um
what 4 things will decreased thiamin abs?
impaired intestinal fxn:
1. alcoholism
2. diarrhea
3. PEM
4. Folate deficiency
Transport of thiamin?
portal vien-> liver and TPP is bound to protein in the plasma. there is facilitated diffusion into RBC and active transport into other cells.
Where is thiamin excreted?
urine in the free thiamin form
What are the assessment methods for thiamin?
1. dietary/medical/family history
2. physical examination
3. lab tets
what lab tests are used to assess thiamin?
1. urinary thiamin excretion
2. blood thiamin level
3. thiamin in CSF
4. bllod pyruvate, lactate and alpha KG levels
5. erythrocyte thansketolase (ETKA) activity on TPP effect on ETKA
Are the measurements to assess thiamin direct or indirect?
indirect
what are the downsides to using the erythrocyte transketolase activity for thiamin status?
tissue thiamin can lose up to 50% of stores before this enzyme starts to decrease in levels, aka show deficiency and the recovery time is slow also. the thaimin levels in teh body can be increased but the enzyme won't be increased
if we use thiamin analogs what happens in cells?
cells take up the analogs not thiamin
is thiamin assessment tissue specific?
yes, there's a large variance between the amounts of thiamin in certian tissues. for example the brain always has a constant level (buffer) but the spleen is greatly effected by little changes
is thiamin assessment greater as the deficiency progresses?
yes, the TPP stimulation is greater as the deficiency progresses. the levels of stimulation depends of the level of deficiency
what is the toxicity for B1?
only at 1000x the RDA
What forms of riboflavin are there?
1. riboflavin which is the abs form
2. FMN- flavin mononucleotide which is riboflavin + P
3. FAD- flavin adenine dinucleotide= ribflavin + ADP
what two forms of riboflavin are cofactors?
FMN and FAD
what two enzymes make FMN and FAD?
1. flavokinase makes FMN by = this rxn riboflavin + ATP -> FMN + ADP

falvokinase expression is enhanced by the thyroid hormone and aldosterone

2. FAD synthetase: FMN + ATP-> FAD + ppi

FAD synthetase has feedback inhibition by FAD
FMN/FAD have what common characteristics?
1. they are cofactors for oxidation/reduction reactions
2. they are donors and acceptors of two protons
3. they are essential in beta- oxidation and the TCA cycle

ex. succinate DH: succinate + FAD ->fumarate + FADH2

fatty acid oxidation:
palmitate + FAD-> palmitic + FADH2
is ariboflavinosis common with other nutrient deficiencies?
yes
symptoms of riboflavin deficiency
-cheilosis
-glossitis
-growth cessation
- cornea vascularization
-skin lesion because a B2 def leads to impaired B6 conversion to its coenzyme which leads maturation of collagen synthesis
-impaired conversion of tryptophan to niacin
what are some predisposing conditions that can lead to riboflavin deficiency?
-lactose intolerance
-kidney dialysis (removes B2)
-hyperthyriodism:drugs suppress flavokinase
-oral contraceptives: high estrogen and depletes circulation riboflavin
-alcoholism
-malabsorption
-chronic stress
what are the two therapeutic things riboflavin is used for?
1. carpal tunnel syndrome: alleviated with B6 and B2 is helpful with B6 activation

2. inborn errors of metabolism: those involving FAD-dependent enzymes and B2 administration is helpful
what is the absorption of riboflavin?
gastric acid releases coenzymes (FAD & FMN) from noncovalent attachment to proteins- pyrophosphatase and phosphatase free riboflavin from FAD/FMN and there is active transport at low conc (Na/K ATPase dep.)
how is it riboflavin transported?
it is transported as riboflavin with binding protein (85%) and albumin (13-15%)
riboflavin cellular absorption
it enhanced thyroid, facilitated diffusion at physiological levels and simple diffusion at higher levels
is there riboflavin toxicity?
no
sources of thiamin
eggs, meats, dairy, broccoli, enriched grain products

it is responsible for yellow color of yolk
requirement of thiamin
1. 0.6 mg/1000 kcal for all ages
2. 1.2 mg/day for intake <2000 kcal
3. Addition 0.3 mg/day for pregnant women
4. Additional 0.4-0.5 mg/day for lactating women
how do you assess the riboflavin?
Activity coefficient (AC): red cell glutathione reductase in presence/absence of exgenous

acceptable level: <1.2
Low: 1.2-1.4
Deficient: >1.4
What are the forms of niacin?
1. Niacin-absorption form (nicotinic acid)
2. Nicotinamide- circulating form
3. NAD, NADP- active cofactor form
what does the active form of the niacin do in the body?
-electron carrier in oxidation/reduction rxns
1. DH
2. ATP production
3. reducing agent
what are characteristics NAD/NADH?
-ATP syn: catabolic
1. glycolysis
2. pyruvate DH
3. TCA cycle oxidation
4. fatty acid oxidation
5. ethanol oxidation
what are the characteristics of NADP/NADPH?
(maintenance & growth: anabolic)
1. fatty acid synthesis
2. cholesterol/steroid syn
3. glutamate DH
4. dNTP synthesis
5. pyr/malate shuttle
what is pellagra and its conditions?
its a niacin deficiency. its signs are weakness, indigestion, lack of appetite, and it progresses to 3 D's: dermatitis, diarrhea, dementia.
what cures pellagra?
50-250 mg/day
what are the predisposition to pellagra?
1. a corn based diet: that is high in leu (imbalanced of EAAs), leu competes for Trp transporter transporter, and leu blocks the synthesis of NAD (bc can be syn by AA Trp)

2. deficiencies of B6, Cu, B2 which are involved in trp -> niacin
synthesis of trp- characteristics?
- the conversation: 1/60
ex 60g of protein = 600 mg trp =10mg niacin

and the first step (oxidase) enhanced 3x by oral contraceptives and pregnancy
what are the therapeutic uses of niacin?
1. hyperlipidemia: 1.5-6 g of niacin (1000x- high levels)
- lowers serum chol and TAG
-average drop is 10-15%
-mechanism uncertain:may interact with membrane receptor, adenylate cyclase, inhibit adipocyte lipolysis thru G protein that inhibits sensitive lipase or decr VLDL syn and secretion in liver

2. CA- help with DNA repair
what are the side effects of the therapeutic doses of niacin?
1. flushing of neck and face
2. itching
3. histamine release
what are the side effects of niacin therapeutic doses partly blocked by?
cyclooxygenase inhibitors (aspirin) given 30 min before niacin
what is the requirement of niacin?
adult: 6.6 mg/1000 kcal
infant: 5-6 mg daily
sources of niacin
meat, liver, legumes, milk, eggs, fish, grain products
how do you assess niacin status?
1. urinary metabolites : N1-methyl-nicotinamide and you are deficient <0.8 mg/day

2.NAD(H)/NADP(H) ratio: ratio>1 adequacy ratio<1 deficiency
what makes up phosphopantetheine?
b-mercaptonethylamine + pantothenic acid + phosphate
what makes up coenzyme A?
b-mercaptonethylamine + pantothenic acid + phosphate + AMP
what is pantothenic acid used for?
the reaction of coenzyme A and forms high energy thio-ester bonds with carboxylic acids, carriers acyl groups in degradation/synthesis reactions
pantothenic acid is used in over 70 metabolic rxns name some
1. high energy bond transfer in glycolysis/ krebs
2. fatty acid oxidation and synthesis
3. steriod/cholesterol synthesis
4. protein modications with fatty acids and isoprenoids
5. acetylcholine, sphingosine synthesis

ex pyr DH, citrate synthase
deficiency of pantothenic acid- is it rare? what are the risk factors?
extremely rare

risk factors: chronic malnutritoin, alcoholism, disruption of GI fxn
what are the symptoms of B5 deficiency?
vomiting, weakness, insomnia, immune impairement, abdominal distress, leg cramps, fatigue, burning cramps, tender heels, growth failure
Protein Modification: with pantothenic acid-acetylation examples
1. need acetylation on the thr, ser, met and sometimes acidic and lysine residues, cytochrome C, actin, histones, DNA-binding proteins: around ~80% of soluble proteins are acetylated at N-terminus
what is purpose of acetylation?
protects from ubiquitination-dependent protein degradation and is required for assembly and stability of 3D protein structures
what is ubinquitination?
a small peptide linked to N-terminus to signal degradation
what is myristolation?
add a Fatty acid protein at the NH2 terminal glycine residue thru amide bond which is irreversible
some examples of proteins that are myristolated
cAMP protein kinase, src
what is the purpose of myristolation?
to protect from ubiqutination and help attach the protein to cell membrane

it is also required for exit from the golgi apparatus