11/12. Thiamine (vitamin B1) Flashcards
11. Structure and metabolism of thiamine (vitamin B1). 12. Biochemical role and deficiency of thiamine (vitamin B1).
1
Q
Structure:
A
-
2
Q
Characteristics of thiamine:
A
- Destroyed in heat, unless the pH is low.
- Thiamine changes into thiachrome when oxidized.
- -> this is the basis for quantitative determination.
- Built up by pryimidine and thiazole
3
Q
Where do you find B1?
A
Fish, meat, milk and outer layer of grains.
4
Q
Metabolism:
A
- Absorbed through duodenum and proximal jejenum, transported to the liver.
- Thiamine can become TPP(thiamine pyrophosphate), by the enzyme thiaminase kinase (atp–>adp) This is a coenzyme in the PPP.
5
Q
Is it stored:
A
In limited amounts in kidney,nerve cells, cardiac muscle.
6
Q
Microbial production?
A
-yes, RU
7
Q
Biochemical role:
A
- Serves as a cofactor in oxidative decarboxylation of alfa ketoacids.
- Cofactor in non-ox part of PPP (transaldolase/transketolase)
8
Q
Reactions where TPP is needed:
A
-
9
Q
Deficiency in human:
A
Beri-beri!
Dry: weight loss, weakness,CNS
Wet: heart damage, edema
10
Q
Deficiency in poultry:
A
Nerve system damage, lameness, retraction of head.
11
Q
Deficiency in sheep and cattle:
A
cortex necrosis
12
Q
Thiaminase:
A
Splits the vitamin, can lead to cerebrocortical necrosis, polyneuritis and paralysis in fur-animals.
Often in raw fish!
13
Q
General deficiency:
A
Less production of ATP, not proper cell function, nerve system can be exposed.
Elevates blood pyruvate level, no pyruvate DH.
