Vitamin B1 or Thiamin Flashcards
Coenzyme of vit B1
TPP (thiamin pyrophosphate)
Coenzyme of vit B2
FAD FMN
Coenzyme of vit B3
NAD/ NADP
Coenzyme of vit B5
CoA
Coenzyme of vit B6
PP
Coenzyme of vit B12
5’ deoxyadenosylcobalamin
Methylcobalamin
Coenzyme of Biotin
Biocytin
Coenzyme of Folate
tetrahydrofolate
Anti-Beriberi Vitamin
THIAMIN or VITAMIN B1
What form and medium is vit b1 dry and stable?
dry form and slightly acidic medium
Vit B1 is Sensitive to _____ or ____ medium, ____ treatment, ____temperature and _____ cooking
neutral or alkaline medium
sulfite treatment
high temperature
prolonged cooking
TPP in GIT is ______ to thiamin
hydrolyzed
______ is carried to the liver via portal circulation
Activated TPP
How vitamin B1 is excreted
all are excreted thru the urine
TPP is a coenzyme for three mitochondrial enzymes involved in the oxidative decarboxylation of α-keto acids:
- Pyruvate dehydrogenase complex
- α-ketoglutarate dehydrogenase
- Branched-chain α-keto acid dehydrogenase
The final common pathway for the oxidation of macronutrients
The TCA Cycle and TPP
a group of enzyme which catalyzes the oxidative decarboxylation of pyruvate to acetyl CoA
Pyruvate Dehydrogenase complex
enzyme that catalyzes in the oxidative decarboxylation of α-keto acids to yield succinyl CoA
α-Ketoglutarate Dehydrogenase
enzyme that catalyzes the oxidative decarboxylation of α-keto acids from valine, leucine and isoleucine
Branched-chain α-keto acid Dehydrogenase
poor sucking, irregular respiration, periodic rigidity and seizures, appear after infants receive a protein-containing feed
maple syrup urine disease
TPP is a coenzyme for transketolase (found in the cytosol). what does it do in the cytosol
Transfer of two-carbon ketol unit from a donor molecule to an acceptor molecule in 2 transketolation reactions
Other roles of Vit B1
- Nerve conduction: controls opening of chloride channels so it could act as a membrane stabilizer
- Nerve impulse transmission: deficiency of enzyme systems may lead to decreased synthesis of neurotransmitters (GABA, acetylcholine et al)
Food Sources
Widely distributed, destroyed by heat, oxidation and ionizing radiation
Food Sources of TPP
Lean pork, pork liver, pork glandular organs, liver and organ meats of other animals, egg yolk
Food Sources of Free Thiamin
unpolished rice, whole grains, legumes, dried yeast, rice bran and wheat germ
DEFICIENCY OF THIAMIN
Early stage:
Loss of appetite, weakness, easily fatigued, GIT disturbances (indigestion and severe constipation), poor reflexes, irritability, retarded growth, and numbness of extremities
DEFICIENCY OF THIAMIN
Later stage:
◦Beriberi or Nutritional Polyneuritis- changes in GI, cardiovascular, and nervous system
◦Infantile Beriberi - in infants 2-5 months whose main nourishment is from a mother with beriberi
type of beriberi that has an edema in the lower extremities which progresses to the body cavities (abdomen and chest); enlarged heart, arrhythmias, breathing difficulty
Wet Beriberi
type of beriberi that has a characteristics of muscle wasting, aphonia, whining cry, cyanosis, difficulty in breathing, may lead to death within a few hours
Dry Beriberi
THIAMIN DEFICIENCY: Seen in alcoholics (pregnant women with excessive vomiting)
◦Symptoms: short-term memory loss, mental deterioration, disorientation, abnormal perception, jerky eye movements, sudden heart failure if untreated
Wernicke-Korsakoff Syndrome
Thiamin is stable in ___ ___ and easily destroyed by ___ and ____
- dry heat
- alkalis and sulfites
most of the thiamin in food is absorbed in an ____ medium
Acidic
CHO ____ the needs of thiamin
Increase
Fats and CHON ____ thiamin
spare
Outstanding food sources of thiamin
Lean pork, pork liver and other glandular organs of pork and some shellfish
