Flashcards in 3 Biotin Pantacid Deck (60):
Biotin family of vitamins?
Biotin is found in
Egg White Injury
Eating raw egg white cause deficiency
- dermatitis (rash, red scaley, around eyes, nose and mouth)
- hair loss (thinning or colour loss)
- neurological abnormalities (depression, hallucinations, parethesia of extremities)
What bind biotin in raw egg white
3 structural features of free-biotin
1. ureido ring
2. Sulfer Ring
3. Valeric Acid Sidechain
Name of protein bound biotin
- What is bound?
- Boitin plus lysine
Biotin binds to enzymes via?
In food, biotin is bound to
What cleaves biocytin from proteins in foods?
What cleaves Biocytin to form Biotin and Lysine
What inhibits the absorption of biotin?
What form of biotin is absorbed?
Free biotin (released from lysine)
cleaves biocytin to biotin plus lysine
Absorption of biotin occurs?
3 metabolic functions of biotin
1. part of coenzyme for carboxylases
2. CO2 donor to substrates
3. CO2 fixation reactions
4 unique enzymes that depend on Biotin
- what reactions are they involved in?
1. Pyruvate Carboxylase
- glucose metabolism
- regenerates OAA for TCA cycle
2. Acetyl-CoA Carboxylase
- FA synthesis
3. Propionyl CoA Carboxylase
- source of energy - entry to TCA cycle
4. 3-methylcrotonyl CoA Carboxylase
- AA metabolism; leucin degredation
* ALL carboxylase
term to describe biotin-dependent enzymes with biotin attached to them
*** Holocarboxylase Synthase
needed to attach biotin to the lysine residue of the enzyme
--> forms holocarboxylase
what does TPN stand for?
Total Parenteral Nutrition
- used as solution when body needs nutrients without eating
3 causes of biotin deficiency?
decreased absorption (avidin)
Deficiency in enzymes
Deficiency in what enzymes would cause biotin deficiency?
Holocarboxylase Synthase Deficiency propsed to play a role in what other deficiency ?
- single carboxylase deficiency
- multiple carboxylase deficiency
Problems with "pyruvate carboxylase def" resulting from biotin def?
- decreased gluconeogenesis
- increased pyruvate and lactate (substrates that form glucose)
- less glucose produced
Problems with "Acetyl-CoA carboxylase def" resulting from biotin def?
- Acetyl-CoA buildup; risk of ketosis
- Impaired serum lipids
Ketone bodies used for energy
- can lead to Ketoacidosis; blood acididty
Urinary Metabolites for diagnostics
Accumulate biotin substrates
- beta-hydroxyisovalerate (leucine catabolism intermediate)
- sometimes lactate
Composition tables with Biotin
Not a lot of information about Biotin on composition tables
Foods containing biotin
whole grain cereals
nuts, legumes, peanut butter
*litte in fruit/veges
low info on composition tables
*** Biotin synthesized in?
*** intestinal bacteria
How much biotin can be absorbed?
Urine and decal amounts have more biotin than dietary amounts?
Implications on long term antibiotic use?
- wipe out intestinal bacteria (*** synthesizes biotin)
- digestive health
- pro and prebiotics
Biotin requirement affected by?
- amount of raw egg white
- biotinidase deficiency
- drug interactions; anticonvulsants, biotin depletion
- Pregnancy increases requirements
- pro and prebiotics
how many biotin dependant enzymes are their?
4 * all end in "carboxylase"
pyruvate, acetyl CoA, propionyl CoA, and 3-methylcrotonyl CoA carboxylase
Name of the group of biotin dependent enzymes
Total parenteral nutrition
Pantothenic Acid absorption
found in many bound forms
intestinal enzymes cleave free pantothenic acid for absorption
(similar to biocytin)
Important structural feature of Pantothenic Acid coenzymes structures
SH (thiol) group
- big focus on sulfur
***Pantothenic Acid coenzyme forms
Coenzyme A (CoA)
Acyl Carrier Protein (ACP)
both contain SH (thiol) group
* complicated structures
Reactions PantAcid coenzymes are involved in
Directly involved biochemical reactions
Coenzyme A synthesized from
CoA alternate abbreviation
- stresses the importance of SH
Structure features of CoA
* sulfhydryl tail
* action happens here
Metabolic role of CoA
- Transfers 2 carbon groups (acyl transfer reactions)
- Connects to SH groups
- Central nutrient in metabolism (Acetyl CoA)
(many anabolic/catabolic fates)
Anabolic + Catabolic fates of CoA
acetylation reactions (drugs)
Vitamin part of CoA
4 examples of CoA transfering acetyl groups
oxidative decarboxylation (ex. TCA)
- pyruvate --> acetyl CoA
- alpha-ketoglutarate --> succinyl CoA
(other vits involved?)
FA oxidation (beta-oxidation)
- degradation to acetyl-CoA
Ketone body formation
- cholesterol synthesis HMG CoA
Tightly bound, needed for biological function of protein
- opposed to coenzymes, loosely bound
Acyl Carrier Protein (ACP)
- prosthetic group?
Coenzyme form of pantothenic acid
- pantothenic acid is a prosthetic group of ACP
Reactive feature of ACP
- where is it from?
- from cysteine
ACP part of what enzyme complex?
Fatty acid synthase
- needed for the addition of acyl groups to intermediates to make palmitate
R - C - R
Metabolic role of ACP
- ACP part of FA synthase complex
- acts as a chaperone
ACP added to complex when fat needed (ACP synthetase)
ACP removed fat not needed (ACP hydrolase)
What does pentose phosphate pathway produce that is needed for fatty acid synthesis? (Vitamin)
(also pentose - don't need to know)
Pantothenic Acid food sources
-animal sources (liver, meats, milk)
Pantothenic acid def. side affects
Burning feet syndrome
-WWII prisoners poor nutrition
-pain in toes and feet
not enough known
- found in many foods, deficiency is rare
Pantothenic Acid other name