PANTOTHENIC ACID

a water-soluble vitamin essential in animal metabolism. Pantothenic acid, a growth-promoting substance for yeast and certain bacteria, appears to be synthesized by intestinal flora in the higher animals. It was first isolated from liver in 1938 and was first synthesized in 1940. The vitamin, although widespread in natureespecially in yeasts, liver, kidney, and eggsdoes not occur in a free form in animal tissues. The nature of the bound form was clarified through the discovery and synthesis (194750) of the compound pantetheine, which contains pantothenic acid combined with the compound thioethanolamine. Pantetheine is OHCH3H O | || CH2 - C - C - C - NH - CH2 - CH2 - COOH || CH3OH part of two larger compounds (coenzyme A and acyl-carrier protein) that promote a large number of metabolic reactions essential for the growth and well-being of animals. In the absence of pantothenic acid (or its dietary equivalents: pantetheine, coenzyme A, or acyl-carrier protein), experimental animals fail to grow, develop skin lesions, and frequently show a graying of the hair. A dietary deficiency severe enough to lead to clear-cut disease has not been described in humans.