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, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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A water-soluble vitamin found in many foods; pork, liver, and whole grains are particularly rich sources. It is also known as vitamin B1 or aneurin. The structural formula of thiamine is shown below.
Thiamine deficiency is known as beriberi in humans and polyneuritis in birds. Muscle and nerve tissues are affected by the deficiency, and poor growth is observed. People with beriberi are irritable, depressed, and weak. They often die of cardiac failure. Wernicke's disease observed in alcoholics is associated with a thiamine deficiency. This disease is characterized by brain lesions, liver disease, and partial paralysis, particularly of the motor nerves of the eye. As is the case in all B vitamin diseases, thiamine deficiency is usually accompanied by deficiencies of other vitamins.
(vitamin B1; aneurine), a heterocyclic compound that is one of the water-soluble vitamins. It consists of colorless crystals with a characteristic odor.
Thiamine was first isolated from rice hulls by the Polish scientist K. Funk in 1912 and later was obtained synthetically. In nature, thiamine is synthesized by plants and certain microorganisms; it is found in the greatest quantities in brewers’ yeast, cereal grains, and potatoes. Animals and humans obtain thiamine from food. A shortage of thiamine in the diet results in the appearance of a serious disease, polyneuritis (in beriberi).
The physiological significance of thiamine results from the coenzyme functions of its pyrophosphoric ester, thiamine pyrophosphate (cocarboxylase). The daily requirement of thiamine for humans is 1.5–2 mg. Thiamine and its phosphoric esters and disulfide derivatives are used to treat peripheral neuritis, diabetes mellitus, disorders of the cardiovascular system, and other diseases associated with disruption of carbohydrate metabolism.