Exam 1 Nutrition 2
When there is an imbalance between free radicals and antioxidants in the body (i.e. too many free radicals) it is termed
'oxidative stress'.
what are the two ways in which vitamin c is absorbed
(1) as dehydroascorbic acid, which uses facilitated diffusion and GLUT1-4; and (2) as vitamin C, which has two transporters: sodium ascorbate co-transporter 1 (SVCT1) and sodium ascorbate co-transporter 2 (SVCT2). Vitamin C requires a Na-dependent gradient coupled carrier.
1.Most common cause of: 1) thiamin deficiency 2) niacin deficiency.
1.Thiamin - White rice-based diet; niacin - corn based diet
describe the absorption of vitamin c
absorbed by sodium dependent vitamin c transporters (svct1 and svct2), absorption decreases with intake. Vitamin C does not require digestion prior to being absorbed into the intestinal wall. Absorption of ascorbic acid occurs across the intestinal cell brush border in the small intestine, especially the proximal jejunum, and requires sodium dependent vitamin C transporters (SVCT) 1 and 2.
find the best match mucosa mastication chylomicron
absorption and secretion, chewing, fat transporter
from coa we can form
acetyl CoA (krebs) malonyl CoA (b oxidation) propionyl CoA methylmalonyl CoA succinyl CoA (citric acid)
Most nutrients are absorbed through the mucosa of the intestinal villi by
active transport
4' phosphopantetheine moiety attaches to apoacyl carrier protein to form ___, which is a small component of the fatty acid synthetase complex
acyl carrier protein
NAD functions
most often in energy-producing reactions involving the degradation (catabolism) of carbohydrates, fats, proteins, and alcohol
what is the •Precursor for NAD+, NADP+ synthesis in REDOX reactions
niacin
what is the process of turning niacin into more niacin and melatonin
niacin to tryptophan, tryptophan splits into serotinin to melatonin and 5h1aa to urine and kyruerenine to niacin via nadph,b6,fad
side effects including heart abnormal blood tests, hot flashes skin irritations, liver damage, elevated blood glucose, and peptic ulcers are indicative of what condition
niacin toxicity
___ deficiency causes rough skin, casal's collar, dementia, diarrhea and can lead to death if untreated is
niacin, pellagra
1.Which 2 forms of niacin are absorbed through the apical membrane?
nicotinamide and nicotinic acid
what does vitamin c increase
non heme iron absorption
riboflavin toxicity
none
describe absorption of pantothenic acid
occurs principally in the jejunum by passive diffusion. Absorption is passive in high concentrations and by a shared multivitamin transporter (SMVT) when in low concentrations. This transporter is shared with biotin and lipoic acid. Pantothenic acid from the intestinal cells enter the portal blood for transport to the liver and other tissues. Bacterially produced pantothenic acid is also absorbed via the SMVT in the colon. Panthenol from vitamins is usually absorbed by diffusion and is subsequently converted to pantothenic acid within the intestinal cell. Approximately 50% of pantothenic acid is absorbed. Absorption decreases to about 10% with supplement use in amounts of about 10 times recommendations.
what are the roles of b1-3 b6-7 and b9
thiamine: decarboxylation: transfer of 2 carbon units, dehydrogenase riboflavin: redox, dehydrogenase, niacin: redox pyridoxine: transamination biotin: carboxylatoin folate: transfer of 1 c unit
fadh enters etc at complex 2
this allows for production of 2 atp
thiamin enzis important to fatty acid synthesis due to its requirement as a coenzyme for the pentose phosphate pathway
transketolase
1.The major role of NADH is to transfer its electrons through the ETC, to produce ATP. true or false
true
Biotinidase is freely available on
the brush border, and in intestinal and pancreatic juices secreted into the small intestine, in the plasma, and in multiple cellular locations
which of the following best describes the human gut microbiome
the community of microorganisms that live in the gastrointestinal tract
describe function of NADPH anabolic reactions
the oxidaiton of NADPH provides electrons needed for the biosynthesis of macromolecules: NADPH donates electrons and becomes oxidized NADP+ simple molecules converted to macromolecules: protein, fat, nucleic acid
describe the function of NAD in catabolic pathways
the oxidation of macronutrients is coupled with the reduction of NAD+, it accepts electrons and becomes reduced to NADH this converts macronutrients such as pro, fat, carb to simple molecules, h2o, co2, simple sugars
what is the metabolically active form of thiamin B1
thiamin pyrophosphate tpp
what three vitamins are involved in energy yielding pathways
thiamin, riboflavin and niacin. Riboflavin and niacin have roles as coenzymes.
what are the b complex vitamins responsible for energy production and nutrient metabolism
thiamin, riboflavin, niacin, folate, biotin, pantothenic acid, vita b6 and b12
name b1-7 b9 and b12
thiamin, riboflavin, niacin, pantothenic acid, pyridoxine,, biotin
antithiamin factors may inhibit absorption such as
thiaminases in raw fish, tannic, chlorogenic, caffeic acids
some raw fish have ___ which prevent the absorption of ___
thiaminases, thiamin
HCL is a gastric juice, what is its function
-Converts pepsinogen to pepsin -Denatures proteins -Releases nutrients from organic complexes -Acts as bacteriocide
•Client 1: I am thinking about purchasing Vitamin C supplements. Is it worth the money? What does it do for me? Seems like a lot of money.
1 answer: most do not require it bc it is easier accessible in everyday food. Recommendation is to get it through food and drink
1.Why can't humans convert glucose to vitamin C?
1.Humans lack gulunolactone oxidase
•Client 2: My aunt has been diagnosed with esophageal cancer, I heard vitamin C can help cancer patients. Something about an antioxidant? Should we encourage her to take supplements.
2 answer: explain an antioxidant. Shes under treatment for cancer, any vitamin can interfere with medical treatment
what are the fat soluble vitamins
A, D, E, K
describe thiamin absorption
Absorption in jejunum by diffusion or carriers: ThTr1 and ThTr2 •Ethanol interferes with absorption •Transported free, bound to albumin, or as thiamine monophosphate (TMP) •Most thiamin in body exists as TDP
describe acetyl coa
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.
what makes vitamin c an effective antioxidant
As Vitamin C acts as a reducing agent or electron donor
describ biotin and egg whites
Biotin is free (unattached) or bound covalently to protein. In raw egg whites, a glycoprotein called avidin irreversibly binds biotin in what has been suggested as the tightest noncovalent bond found in nature. This binding to avidin in turn prevents biotin absorption. Avidin is heat labile - eating cooked egg whites does not compromise biotin absorption.
describe the formation of coa
Carboxyl group from the cysteine moiety is removed by phosphopantethenylcysteine decarboxylase to form 4' phosphopantetheine moiety: required for the acyl carrier protein (ACP) - a component of the fatty acid synthase complex.
is the key protein that regulates the ETC from NADPH to various monooxygenases. Electron transfer via FAD and FMN (i.e. NADPH to FAD to FMN to monooxygenase).
Cytochrome reductase (aka Coenzyme Q)
describe the functions of vitamin c
Essential component of wound healing, collagen synthesis, antioxidant and supports regeneration of other antioxidants - which may help with chronic diseases such as cancer, immune function, absorption of nonheme iron,
Within intestinal cell, riboflavin may be phosphorylated to form
FMN in a reaction catalyzed by flavokinase and requiring ATP.
which cofactor is not involved in the metabolic pathway of pyruvate to acetyl coa
FMn
what are free radicals
Free radicals are atoms or molecules that are highly reactive with other cellular structures because they contain unpaired electrons. Free radicals are natural by-products of biochemical reactions in the body. Free radicals can cause damage to the parts of the cells such as proteins, DNA and cell membranes by stealing their electrons through oxidation. This why free radical damage is also called 'oxidative damage'.
describe riboflavin transporter deficiency
Genetic defects in RFVT2 and RFVT3 lead to neurodegenerative disease that affects cranial nerves. Deafness and vision loss may occur. Sometimes referred to as Brown-Vialetto-Van Laere syndrome.
in the stomach, riboflavin is freed from proteins by
HCl and gastric enzymes
L-amino acid oxidase uses FMN in the dehydrogenation of
L-amino acids to inimo acids.
what is the enzymes called that we lack that is derived from glucose, it is the last enzyme in the vitamin c synthetic pathway to finish the metabolism of glucose
L-gulonolactone oxidase
b5 main functions
Main functions: -Acyl transfer reactions -Acetylation/acylation of proteins, sugars, and other substrates -Gene expression
major food sources of biotin
Major food sources include liver, milk, soybeans and yogurt as well as cereals.
nadp function
NADP generally serves in biosynthetic (anabolic) reactions, such as in the synthesis of fatty acids, steroids (e.g., cholesterol, bile acids, and steroid hormones), and building blocks of other macromolecules (4). NADP is also essential for the regeneration of components of detoxification and antioxidant systems (4).
what does the hmp pathway generate
NADPH for synthetic operations and ribose for nucleic acid synthesis.
pantothenic acid in the blood
Pantothenic acid is typically found free in the blood, primarily in the red blood cells. Blood concentrations usually range from 30-60ug/dL. Uptake into the red blood cells is via diffusion, but some tissues/organs require SMVT. Most pantothenic acid is found in all tissues, but in fairly high concentrations in the liver, adrenal glands, kidneys, brain, and heart. Pantothenic acid, 4'-phosphopantethenic acid, and pantetheine are all present within cells.
describe digestion of pantothenic acid
Pantothenic acid occurs in free form and bound forms. About 85% of the pantothenic acid in food is bound as a component of coenzyme A. During digestion in the small intestine, CoA is hydrolyzed by pyrophosphatase to 4′-phosphopantetheine, which is then dephosphorylated by phosphatase to pantetheine, which is converted to pantothenic acid by pantotheinase.
describe nerve supple of small intestine
Parasympathetic innervation via vagus nerve, and sympathetic innervation from thoracic splanchnic nerves
What is niacin deficiency?
Pellagra: 4D: •dermatitis, diarrhea, dementia, and death
describe proprionyl coa
Propionyl-CoA is later converted into succinyl-CoA through propionyl-CoA carboxylase (PCC) by the use of vitamin B12. Catabolism of amino acids can also be a result of the conversion of propionyl-CoA to methylmalonyl-CoA by propionyl-CoA carboxylase.
riboflavin leaves the enterocyte via
RFVT1 RFVT2
genetic defects in which of the following could potentially lead to deafness and vision loss
RFVT2, RFVT3
Riboflavin has three absorption carriers: RFVT1, RFVT2, and RFVT3. describe the transport locations
RFVT3 - transport across apical membrane RFVT1 - transport across basolateral membrane RFVT2 is involved in brain transport of riboflavin but can also absorb via small intestine.
is an FAD flavoprotein which removes succinic acid to form fumarate, and that forms FADH2 from FAD. The electrons are then passed into the ETC by Coenzyme Q.
Succinate dehydrogenase
describe blood supply of small intestine
Superior mesenteric artery brings blood supply Veins (carrying nutrient-rich blood) drain into superior mesenteric veins, then into hepatic portal vein, and finally into liver
what is tpp
TPP is a coenzyme in the BC a-ketoacid dehydrogenase (BCKDH) complex which is critical for metabolism of leucine, isoleucine, valine. Defiiency of this enzyme leads to maple syrup urine disease (MSUD).
describe thiamins strucutre
Thiamin's structure is a pyrimidine ring and a thiazole moiety (one of two parts linked by a methylene bridge. Methylene bridge can be split by sodium bisulfite or enzyme thiaminase (fish).
which of the following vitamins allows iron to be a viable cofactor for the enzymes prolyl hydrolase an d lysyl .hydroxylase used in collgen production
VITAMIN C
Neurotransmitter synthesis Hydroxylation of Phenylalanine: what is needed to regenerate tetrahydrobiopterin from dihydrobiopterin.
Vitamin C
how is vitamin c transported in the blood. and where is it stored
Vitamin C is transported in blood in the form of free ascorbic acid or dehydroascorbic acid (minor amounts) and is primarily sto red in adrenal and pituitary glands, eyes, brain, white blood cells.
reaction of pyruvate to acetyl coa produces
a NADH which will enter the ETC.
coa functions as
a carrier of Acetyl/acyl groups, forming thioester derivatives named above. CoA facilitates biological acetylation reactions.
who becomes deficent with thiamin
alcoholics, malnourished
what is beriberi
an acute, progressive neuropathy with impairment of both superficial and deep sensation and motor weakness.
describe succinyl coa
an intermediary of the citric acid cycle, generated by decarboxylation of α-ketoglutarate. Succinyl Co-A is needed to synthesize the porphyrin ring in heme.
ulcerations or erosions in the mucosa and submucosa layers of the stomach, esophagus and duodenum is referred to as peptic ulcer disease. which of the following is not a typical causative factor for the development of ulcers in the digestive tract
antihistamines
high pharmacological dose of nicotinic acid can be used as a ___ treatment
antihyperlipidemia
Once riboflavin converted to coenzymes, the flavin coenzymes become bound to
apoenzymes (inactive enzymes). Once bound, FMN and FAD form part of the flavoproteins that are involved in redox reactions.
sores on the lips and cuts on the edges of the mouth are early symptoms fo
ariboflavinosis
what is vitamin c known as
ascorbic acid
describe ileum
attached posteriorly by mesentery; joins large intestine at ileocecal valve
what are the water soluble vitamins
b complex and vitamin C
whats the other name for riboflavin
b2
what is the symbol for niacin
b3 , nicotinic acid and nicotinamide
what is the symbol for pantothenic acid
b5 •First identified as a growth factor for yeast and an anti-dermatitis factor in chicks
which substance is enteroheptatically circulated
billiary acids
hair loss associated with eating raw eggs may be revered by treatment with
biotin
overconsumption of egg white may lead to a deficiency of biotin due to which of the following reasons
biotin is bound to avidin preventing the absorption across luminal membrane
what are the b complex vitamins responsible for gene expression
biotin, pantothenic acid, folate, and vitamin b6
why are patients with pancreatitis usually provided with nutrients that are partially hydrolyzed
body unable to produce sufficient quantities of pancreatic enzymes
find the best match salivary amylase, bolus, peristalsis chyme
breakdown CHO/starch, mass of food from chewing, gi tract motility, partially digested food
how is biotin made
by bacteria in colon
describe a severe riboflavin deficiency
can impair the metabolism of other nutrients, especially other B vitamins, through diminished levels of flavin coenzymes. Anemia and cataracts can develop if riboflavin deficiency is severe and prolonged.
Riboflavin facilitates the release of energy from
carbohydrates, fat and protein through the Kreb's cycle, mitochondrial ETC, and other electron transfer mechanisms. Riboflavin may also be involved in protein stabilization and regulate apo-protein synthesis.
what should you think of when thinking biotin
carboxylation adding CO onto Acetyl CoA).
Symptoms of wet beriberi
cardiac enlargemnt with pedal edema
what are the four main regions of the stomach
cardiam fundus, body, antrum or distal pyloric region
tpp functions as a
coenzyme for cytosolic transketolase reaction.
tpp acts as a
coenzyme in to α-ketoglutarate dehydrogenase complex to facilitate the conversion α-ketoglutarate to Succinyl CoA.
which of the following is not a role of thiamin in energy metabolism
cofactor for the enzymes NAD and NADH
vitamin c acts as a cofactor by maintaining iron in a reduced in
collagen synthesis
riboflavin is transported to liver for
conversion to FMN and FAD
riboflavin transported to liver for
conversion to fmn and fad
describe duodenum
curves around head of pancreas Has most features
FAD is coenzyme for
cytochrome reductase, pyruvate dehydrogenase complex, succinate dehydrogenase,
Describe Ariboflavinosis
deficiency disease due to inadequate intake of riboflavin and characterized by sores on the mouth. The signs and symptoms of riboflavin deficiency (I.e. ariboflavinosis) include skin disorders, hyperemia (excess blood) and edema of the mouth and throat, angular stomatitis (lesions at the corners of the mouth), cheilosis (swollen, cracked lips), hair loss, reproductive problems, sore throat, itchy and red eyes, and degeneration of the liver and nervous system.
individuals with alcohol dependency are at an increased risk of alcoholic pellagra encephalopathy. Watch this video and read the main comment below the video from the neurology journal to observe an individual with alcholic pellagra encephalopathy. which one of the following statements is not a causative factor for this condition
deficiency in the thiamin diphosphotransferase enzyme
what are the direct and indrect benefits of niacin
direct: low dose: pellagra, high dose: hyperlipidemia indirect: redox
what is mucus secreted by
duodenal glands and goblet cells of mucosa
what are the three structures in the small intestin
duodenum, jejunum, and ileum
Antioxidants, are free radical scavengers, which are compounds that
either reduce the formation of free radicals or react with and neutralize them
describe thiamin
exists in free form in plant foods, in animal foods, primarily as thiamin diphosphate (tdp), formerly known as tpp. digestion: phosphorylated in intestine
TPP acts as a coenzyme within the pyruvate dehydrogenase complex to
facilitate the conversion of pyruvate to Acetyl CoA.
FMN donated two hydrogen electrons in complex 2 of the etc true or false
false
FMN and FAD act as prosthetic groups for enzymes called
flavoproteins
The enzymes containing riboflavin are called
flavoproteins; these enzymes catalyze oxidative-reduction reactions
complex 1 of the etc requires
fmn
what are the b complex hematopoietic vitamins
folate and vitamin b12
what occurs in the stomach
food converted to chyme by mixing with gastric juice
Dietary fat intake has an inhibitory effect on
gastric emptying
most animals synthesize their own ascorbic acid from
glucose
Similarly, niacin is functional as NAD or the phosphorylated form, NADP. Both forms are reduced in
glycolysis and the Krebs cycle and transfer electrons to the electron transport chain for ATP formation.
mods of thiamin by adding an OH group to the vitamin results in oxythiamin, which
has antivitamin activity and can exacerbate thiamin deficiency symptoms such as those affecting the nervous system
function of biotinidase
hydrolyzes the biocytin to release free biotin and lysine.
where are the greatest concentrations of riboflavin found
in liver, kidney, and heart
Who gets Niacin deficiency:
include inadequate oral intake, poor bioavailability from unlimed grains, defective tryptophan absorption, metabolic disorders, and the long-term use of chemotherapeutic treatments.
pancreatic juice that enters the duodenum through the sphincter of oddi contains all of the following except
intrinsic factor
what is succinate dehydrogenase
is an FAD flavoprotein which removes succinic acid to form fumarate, and that forms FADH2 from FAD. The electrons are then passed into the ETC by Coenzyme Q
describe the order in which food is digested
it is ingested and mechanically broken down by chewing then goes to the pharynx to the esophagus by propulsion via swallowing (oropharynz) and peristalsis from here it goes into the stomach where churning begins and digestion begins, food then travels to SI to begin segmentation. Here nutrients are absorbed into the blood an lymph vessels. lastly it travels to large intestine and turned into poop
describe vitamin C
its an antioxidant, and enzyme cosubstrate
Following uptake in the cells, riboflavin is converted into
its coenzyme forms. FMN is the major form in cells (60-95%) followed by FAD (5-20%).
which of the following patients would most benefit from riboflavin supplemenation
jaundice newborns
Nicotinic acid can be synthesized from Tryptophan via - very inefficient as it requires 60 mg of Tryptophan to create 1 mg of nicotinic acid. Accounts for 3% of tryptophan utilization
kynurenine pathway
Which of the following are not considered high risk groups of riboflavin deficiency
lactovegetarians
where is the greatest concentration of riboflavin found
liver, kidney, heart
symtoms of dry beriberi
loss of tendon reflexes, burning or tingling, numb feet, emaciation, confucion, inability to speak, wrist drop, foot drop symptoms are neurological
vitamin C has been shown to have a beneficial role in the prevention and treatment of cardiovascular disease. which of the following has been shown to improve with chronic supplementation (>500 mg/day) of vitamin C
lower total cholesterol
what is niacins function with low and high doses
lwo: b3, nicatinamide high dose: antihyperlipidemic
Peristaltic waves propel digestive contents Basic electrical rhythm initiated by
pacemaker cells
most of the enzymes involved in digestion are produced by the
pancreas
Pantothenic acid is composed of two molecules:
pantoic acid and the amino acid alanine.joined by an amide linkage.
synthesis of coenzyme A starts with the phosphorylation or which vitamin
pantothenic acid
what are the enzymes present in the stomach
pepsin, amylase, and lipase
match the enzyme to their substrate/function amylase, lipase, pepsin
polysaccharides, tgs, protein- stomach
which of the following is not a function of the liver
production of gastric juice
what is the function of the pharynx
propels food from back of the oral cavity into the esophagus
what do fmn and fad function as
prosthetic group for enzymes. They both function as coenzymes for a variety of oxidative enzymes and remain bound to the enzymes during the oxidative-reduction reactions. Flavins can act as oxidizing agents because of their ability to accept a pair of hydrogen atoms.
match the enzyme to their substrate/function trypsin, bile cck
protein- si emulsification of fats stimulates the release of bile and pancreatic juices
both wet and dry beriberi are due to vitamin b1 deficiency. each affecting different systems within the body. what signs and symptoms are not typically present in individuals with dry beriberi
pulmonary hypertension
what are enzymes that require cofactors
pyruvate dehydrogenase in glycolysis a ketoglutarate deydrogenase in krebs , and bc a keto acid dehydrogenases transketolases in the hmp chunt
TDP (or TPP as formerly known) is involved in the oxidative decarboxylation of
pyruvate to acetyl CO-A, a-ketoglutarate to succinyl Co-A, and of the three branched chain amino acids (leucine, isoleucine, and valine).
thiamin is needed for reactions involving the metabolism and release of energy from carbohydrates. which of the following reactions does not require thiamin
regeneration of tetrahydrobiopterin
what does refining of grain mean
removal of outer later of grain, white rice or bread has no thiamin
how is riboflavin digested in the intestine
riboflavin freed from proteins by intestinal enzymes b. FAD and FMN converted to riboflavin c. riboflavin phosphate hydrolyzed by phosphatases to riboflavin FAD pyrophosphatase converts FAD to FMN, and FMN in turn is converted to free riboflavin by FMN phosphatase.
describe the absorption of free riboflavin
riboflavin is absorbed across the intestinal brush border membrane by an energy-dependent riboflavin vitamin transport 3 (RFVT3). Another riboflavin transporter, RFVT1, carries riboflavin across the basolateral membrane of intestinal cells
what are the three methods to optimize absoprtion in intestinal wall
rugae, villi, and microvilli
Salivary glands produce salivary amylase to breakdown cardohydrates into
saccharides
Describe gastric juice
secreted daily in response to distension or irritation of mucosa Major stimulus for production is hypertonic or acidic chyme Slightly alkaline and isotonic with blood plasma Consists largely of water but also contains mucus
what is the major organ of digestion and absorption
si
in general, in which portion of the gastrointestinal tract does most absorption occur
small intestin
match the enzyme to their substrate/function gastrin CP450
stimulates the relase of gastric acid detoxifiation within liver
Gastric emptying affected by factors in
stomach and duodenum
FAD is a conenzyme for _____ which converts succinate to fumarate
succinate dehydrgenase
what is the main carrier responsible for vitamin c absorption
svct1.SVCT 1 enables absorption of the vitamin in excess of cell needs, but is downregulated by ascorbic acid, which limits absorption when superphysiological doses are ingested.
what is niacin transported primarily as
• nicotinamide and as nicotinic acid
where can niacin be derived from
tryptophan
what can inactivate riboflavin and its derivatives
uv and light.Because of this sensitivity, lengthy light therapy to treat jaundice in newborns or skin disorders can lead to riboflavin deficiency. The risk of riboflavin loss from exposure to light is the reason why milk is not typically stored in glass containers.
which of the following vitamins is used in multiple reactions involving the conversion of the amino acid phenylalanine to the neurotransmitters such as L-dopa and norepinephrine
vitamin C
what is scurvy and what deficiency is it
vitamin c. The man had loose teeth and bleeding gums. The follicles of the skin are plugged with keratin.perifollicular hemorrhage
difference between coenzymes and cofactos
vitamins have both, coenzymes bind to active sites minerals only have cofactors, they dont bind
Riboflavin plays a role as FAD and FMN which facilitate
which facilitate the release of energy from macronutrients via the Krebs cycle.
describe microvilli
§Cytoplasmic extensions of mucosal cell that give fuzzy appearance called the brush border that contains membrane-bound enzymes brush border enzymes, used for final carbohydrate and protein digestion
describe villi
§Fingerlike projections of mucosa (~1 mm high) with a core that contains dense capillary bed and lymphatic capillary called a lacteal for absorption
Vitamin c's main function is as an antioxidant, describe its role as a cosubstrate for enzyme activity
ØReducing agent in collagen synthesis ØCofactor in Carnitine synthesis ØCofactor in Catecholamine synthesis As a cosubstrate, some enzymes contain a mineral (copper or iron) cofactor and vitamin C functions as a reducing agent to maintain the iron and copper atoms in the reduced state.
how does the absorption of pantothenic acid occur
•Absorption occurs by a passive process (about 50% efficiency) and also by sodium dependent shared multivitamin transporter (SMVT) carrier that is also used by biotin and lipoic acid.
Pantothenic Acid Deficiency
•Burning foot syndrome (and neuritis) •Most likely to occur with: •multiple nutrient deficiencies: abject poverty, anorexics •Alcoholics •Diabetes mellitus •Inflammatory bowel disorders
Pantothenic Acid (B5) is used to make COA, Coa function
•Coenzyme A activates molecules, allowing them to go forward in various energy pathways.
describe metabolism and function of biotin
•Coenzyme carrier for the transfer of 'activated bicarbonate' to substrates. THINK 'carboxylation •Nutrient metabolism and energy production •Non-coenzyme roles: biotinylation, gene expression
what are some other functions of vitamin c
•Collagen formation is dependent on vitamin C metabolism. •Vitamin C can reduce iron to the ferrous form, which is more available for intestinal absorption. •It is central in two reactions in the formation of carnitine to allow for longer chain fatty acids to cross the inner membrane of mitochondria for β-oxidation.
functions and mechanisms of action of pantothenic acid
•Component of CoA and 4'-phosphopantetheine •Nutrient metabolism •Acetylation of proteins, sugars, drugs •Prosthetic group for acyl carrier protein (ACP) - FA synthesis
high risk groups of riboflavin toxicity
•Congenital heart disease, some cancers, excess alcohol intake sure to poor dietary intake •Those in developing countries •Thyroid disease •diabetes
thiamin functions and mechanisms of action
•Energy production and nutrient metabolism (coenzyme role) •Synthesis of pentoses and nicotinamide adenine dinucleotide phosphate (NADPH) (coenzyme role) nervous system functions (noncoenzyme role)
thiamin deficiency symptoms
•Enlarged heart •Cardiac failure •Muscular weakness •Apathy •Short Term Memory Loss •Confusion •Irritability •Anorexia, Weight loss •In alcoholics, cerebral beriberi and psychosis (Wernick Korsakoff syndrome)
•Riboflavin is the vitamin form. what are the Two co-enzyme forms:
•FMN (flavin mononucleotide) •FAD (flavin adenine dinucleotide)
what are the roles of riboflavin
•Flavoproteins in ETC •Vitamin B6 metabolism •FMN is used in the conversion of PMP and PNP to PLP (primary form) •Dehydrogenation of L amino acids to imino acides using FMN dependent L amino oxidase
what are the four Hs of scurvy
•Hs of scurvy •Hemorrhagic signs •Hyperkeratosis of hair follicles •Hypochondriasis (psychological manifestation) •Hematologic abnormalities •Treated with 100-500 mg daily until cured
what are the early symptoms of riboflavin deficiency
•Hyperemia (red, bloody mouth) •Oculo-orogenital syndrome: seborrheic dermatitis, anemia, peripheral nerve dysfunction
describe niacin toxicity
•Large doses used to treat hyperlipidemia (nicotinic acid) •UL = 35 mg/day
assessment of nutriture of thiamin
•Measuring erythrocyte transketolase activity in hemolyzed whole blood •Measuring thiamine in blood or urine
toxicity of thiamin
•No Tolerable Upper Intake Level established •>125 mg/kg can cause Sx: edema, nervousness, sweating, tachycardia...
toxicity for pantothenic acid
•None reported •Higher intakes > 15-20 g/day: mild intestinal distress, diarrhea
describe biotin absortion
•Only free biotin can be absorbed via the SMVT. •absorbed in colon via SMVBiocytin must be hydrolyzed by biotinidase. Intestinal bacteria
what is the function of riboflavin
•Plays a crucial role in metabolic reactions and is critical for normal cellular functions, growth, and development.
pantothenic acid
•Serves as a component of acyl carrier protein (ACP), which is important in fatty acid synthesis. •Derivatives include acetyl-CoA, succinyl Co-A, propionyl Co-A. •involved in the metabolism of carbohydrates, protein, fat, and ethanol.
describe biotin digestion
•protein bound biotin requires digestion by enzymes. •Proteolysis yields biotin or biocytin (biotin bound to amino acid lysine). •Biotinidase deficiency
what can riboflavin be ingested as
•riboflavin •FAD •FMN •riboflavin phosphate
symptoms of pantothenic deficiency
•vomiting, fatigue, impaired motor function, cramps, disturbances in the GI tract, ulcers, cardiac problems, hypotension, reduced eosinophil output, hypochromic anemia, and hypoglycemia