Chemistry of Thiamine
Thiamine is a colorless compound with the chemical
formula C12H17N4OS.
It is
soluble in water and
insoluble in alcohol. Thiamine decomposes if heated.
It consists out of a
pyrimidine- and a thiazol ring, which are synthesized independently and linked
afterwards.Vitamin B1 is de novo produced by many plants and microorganisms. Humans
and animals have to take it up by nutrition. They are only able to do the phosphorylation
reaction of the thiamin molecule. Thiamin is found free and as mono-, di- and triphosphate.
The different forms can be transfered into each other. The metabolic active form is thiamin
diphosphate in the body and thiamin triphosphate in the brain.
Thiamin diphosphate
(TDP) works as thermostable coenzyme in many enzymes of the carbohydrate and
amino acid metabolism. In most reactions TDP catalyzes the cleavage of C-C
bonds.
In the nervous
system vitamin B1 is needed for the stimulation of nerve cells. The classical disease
of patients with a lack of vitamin B1 is Beriberi, which is known from regions
where people eating predominantly white rice. The symtoms are paralysis, muscle
dystrophia and heart failure. Other diseases are the Wernicke encephalopathy,
the Korsakow syndrome and some forms of the Landry`s paralysis. In
industrialized countries alcoholism seems to be the most important reason for a
lack of vitamin B1. In alcoholics the thiamin resorption is disturbed.
Due to a damage of the liver the storage capacity of
vitamin B1 is reduced.
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