Pantothenate pantothenic acid

Another acid amide bond (-CO-NH-) creates the compound for the next constituent, pantoinate. This compound contains a chiral center and can therefore appear in two enantiomeric forms (see p.8). In natural coenzyme A, only one of the two forms is found, the (R)-pantoinate. Human metabolism is not capable of producing pantoinate itself, and it therefore has to take up a compound of (1-alanine and pantoinate— pantothenate ( pantothenic acid )—in the form of a vitamin in food (see p.366). 

Fig. 8.12. CoA and biotin, activation-transfer coenzymes. A. Coenzyme A (CoA or CoASH) and phosphopantetheine are synthesized from the vitamin pantothenate (pantothenic acid). The active sulfhydryl group, shown in blue, binds to acyl groups (e.g., acetyl, succinyl, or fatty acyl) to form thioesters. B. Biotin activates and transfers CO2 to compounds in car-boxylation reactions. The reactive N is shown in blue. Biotin is covalently attached to a lysine residue in the carboxylase enzyme.

Pantothenate calcium. See Calcium D-pantothenate Pantothenic acid... 

Species A, RE 6 12 C Thiamine Riboflavin Nicotinic acid Pantothenic acid Biotin Fohc acid... 

Sulfur is part of several vitamins and co-factors, eg, thiamin, pantothenic acid [79-83-4] biotin [58-85-5] and Hpoic acid. Mucopolysaccharides, eg. 

The nicotinic acid content of several nuts has been reported (in mg/kg) as follows chestnut, 200 ha2el nut, 600 almond, 1600 and sunflower seed, 5000 (40). The results of analyses for pantothenic acid are (in mg/kg) ha2el nut, 380 almond, 75 sunflower seed, 620 and walnut, 600. Nuts also contain more biotin than most fmits and vegetables. 

Because there is less information upon which to base dietary allowances for biotin and pantothenic acid, ranges of intake are provided, as in Table 8. 

After a full stmctural elucidation of coen2yme A ia 1953 by Baddiley, it became evident that pantothenic acid is one of the components of coen2yme A (2)... 

Biosynthesis of coen2yme A (CoA) ia mammalian cells incorporates pantothenic acid. Coen2yme A, an acyl group carrier, is a cofactor for various en2ymatic reactions and serves as either a hydrogen donor or an acceptor. Pantothenic acid is also a stmctural component of acyl carrier protein (AGP). AGP is an essential component of the fatty acid synthetase complex, and is therefore requited for fatty acid synthesis. Free pantothenic acid is isolated from hver, and is a pale yeUow, viscous, and hygroscopic oil. 

Relatively Httie is known about the bioavailabiUty of pantothenic acid in human beings, and only approximately 50% of pantothenic acid present in the diet is actually absorbed (10). Liver, adrenal glands, kidneys, brain, and testes contain high concentrations of pantothenic acid. In healthy adults, the total amount of pantothenic acid present in whole blood is estimated to be 1 mg/L. A significant (2—7 mg/d) difference is observed among different age-group individuals with respect to pantothenic acid intake and urinary excretion, indicating differences in the rate of metaboHsm of pantothenic acid. 

R)-Pantothenic acid (1) contains two subunits, (R)-pantoic acid and P-alanine. The chemical abstract name is A/-(2,4-dihydroxy-3,3-dimethyl-l-oxobutyl)-P-alanine (11). Only (R)-pantothenic acid is biologically active. Pantothenic acid is unstable under alkaline or acidic conditions, but is stable under neutral conditions. Pantothenic acid is extremely hygroscopic, and there are stabiUty problems associated with the sodium salt of pantothenic acid. The major commercial source of this vitamin is thus the stable calcium salt (3) (calcium pantothenate). 

Panthenol (4) is the reduced form of pantothenic acid and is the pure form most commonly used. The alcohol is more easily absorbed and is converted iato the acid m vivo (12). Both panthenol and pantyl ether are used ia hair care products. 

Table 1. Physical Properties of Pantothenic Acid and Derivatives...

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