Pantothenic add

Fatty add synthase is a large multienzyme complex in the cytoplasm that is rapidly induced in the liver after a meal by high carbohydrate and the concomitant rise in insulin levels. It contains an acyl carrier protein (AGP) that requires the vitamin pantothenic add. Althoi malonyl CoA is the substrate used by fetty acid synthase, only the carbons from the acetyl CoA portion are actually incorporated into the fatty acid produced. Therefore, the fetty add is derived entirely from acetyl CoA. 

The remaining series of reactions of fatty acid synthesis in eukary-l otes is catalyzed by the multifunctional, dimeric enzyme, fatty acid synthase. Each fatty acid synthase monomer is a multicatalytic polypeptide with seven different enzymic activities plus a domain that covalently binds a molecule of 4 -phosphopantetheine. [Note 4-Phosphopantetheine, a derivative of the vitamin pantothenic add (see p. 379), carries acetyl and acyl units on its terminal thiol (-SH)j group during fatty acid synthesis. It also is a component of 00-enzyme A.] In prokaryotes, fatty acid synthase is a multienzyme complex, and the 4 -phosphopantetheine domain is a separate protein, referred to as the acyl carrier protein (ACP). ACP is used below to refer to the phosphopantetheine-binding domain of the eukaryotic fatty acid synthase molecule. The reaction numbers in1 brackets below refer to Figure 16.9. [Note The enzyme activities listed are actually separate catalytic domains present in each mulf-1 catalytic fatty acid synthase monomer.]... 

Antagonists of biotin include desthiobiotin in some forms, ureylene phenyl, homobiotin, urelenecyclohexyl butync and valeric acid, norbiotin, avidin, lysolecithin. and biotin sulfone. Synergists indude vitamins B>. B6, B 2, folic acid, pantothenic add. somatotrophin (growth hormone), and testosterone. 

In 1901. Wildiers described Bios, an essential for yeast growth. In 1933. Williams isolated crystalline Bios from yeast and named it pantorhemc acid. In 1938, Williams isolated pantothenic acid from liver and. in 1939, Jukes determined liver antidermatitis factor (chick) to be identical with yeast factor. Also, in 1939, Woolley et al. demonstrated beta-alanine as a vital part of pantothenic add ... 

Distribution and Sources. Particularly high in pantothenic add content are yeasts, animal glands and organs. Fruits have a low content. 

Several biotechnological synthetic methods for D-pantothenic add and its precursor D-pantolactone have been developed over the past 15 years. Although all have reached preparative scale and might result in cost-effective production processes, they differ considerably in their process characteristics - for example educts and space-time yields, especially when a fermentation and biotransformation are compared. Compared with the chemical process, the biotechnological processes reduce waste production and provide the possibility of a more environmentally friendly yet still competitive means of production of D-pantothenic acid. 

Pantothenic add (Vitamm B3) Eggs, peanuts, liver, meat, milk, cereals, vegetables Vomiting, abdommal distress, cramps, fatigue, insomnia. 

The average intake of pantothenic add, as free pantothenic add and as coenzyme A, acetyl-ooenzyme A, and long-chain fatty acyl-cocnzyme A, is S to 10 mg/day. An RDA for the vitamin has not been established because the vitamin is plentiful in a variety of foods. Pantothenic acid is present in all plant and animal foods. The richest sources of the vitamin are liver, yeast, egg yolk, and vegetables. In foods, the vitamin occurs mainly as coenzyme A,... 

Coenzyme A does not readily cross cell membranes, including those of the gut Dietary coenzyme A is hydrolyzed in the gut lumen to yield pantothenic add, which is readily absorbed. Studies with rats have shown that coenzyme A is hydrolyzed in the gut lumen according to the pathway in Figure 9.76. 

The serum level of pantothenic add is about 1 to 5 lM (Lopaschuk d ai, 1987). The vitamin in the bloodstream is transported into various tissues, where it is then converted to coenzyme A. Coenzyme A is synthesized from pantothenic add, ATP, and cysteine. The pathway of coenzyme A synthesis is shown in Figure 9,77. The cofactor of fatty add synthase is synthesized from coenzyme A and does not involve the direct participation of pantothenic acid. A specific enzyme catalyzes... 

Pantothenic add levels in foods and body fluids can easily be measured by microbiological assays. Lactic acid bacteria are used as the test organism. Where measurement of ihe vitamin occurring as coenzyme A is desired, the coenzyme must first be treated virlth hydrolytic enzymes to liberate the pantothenic acid prior to the microbiological assay... 

Pantothenic add, 492, 493, 613-617 Pantothenic add defidency, 493, 6) 7 ParaceUular pathway, 717 Parasitic infeclicins anemia and, 759 vitamin Biz deficiency, 521 Parathyroid gland... 

Urinary excretion of pantothenic add of less than 1 mg/day is considered abnormally low. Suspicion of inadequate intalce is further supported if whole blood levels are less than lOOpg/L, A guidance reference interval for pantothenic acid in whole blood or serum is 344 to 583(ig/L (1,57 to 2.66pmol/L), and for urinary excretion is 1 to 15 mg/day (5 to 68 uLmol/day). ... 

Brackett, S., Waletzky, E., and Baker, M. (1946). The relation between pantothenic add and Plasmodium gallinaceum infections in the chicken and the antimalarial activity of analogues of pantothenic acid.. Parasitol. 32, 453-462. 

CoASH is synthesized from the vitamin pantothenate in a sequence of reactions which phos-phorylate pantothenate, add the sulfhydryl portion of CoA from cysteine, and then add AMP and an additional phosphate group from ATP (see Fig. 8.12). Pantothenate is widely distributed in foods (pantos means everywhere), so it is unlikely that Ann O Rexia has developed a pantothenate deficiency. Although CoA is required in approximately 100 different reactions in mammalian cells, no Recommended Daily Allowance (RDA) has been established for pantothenate, in part because indicators have not yet been found which specifically and sensitively reflect a deficiency of this vitamin in the human. The reported symptoms of pantothenate deficiency (fatigue, nausea, and loss of appetite) are characteristic of vitamin deficiencies in general. 

Pantothenic add is most stable in a slightly addic medium (pH 4-5). Bolh in acid and alkali it is cleaved. The salt form of pantothenic acid is even more stable. CoA is relatively stable in solutions of pH 2-6. 

PUutothenie acid is a widely distributed compound in animals and plants, consisting of 2,4-dihydroxy-33-dimethylbutync acid (pantoic acid) linked to alanine by an amide bond Most organisms have the abili to synthesize pantoic acid from valine, and P-alanine from asparate, but humans lack the enzyme, pantothenate synthetase, which catalyses the condensation of p-alanine and pantoic acid to form pantothenic add Only the n(-i-)-form of pantothenic add is biologically active. It is required for the synthesis of Coenzyme A (see). Non-experimental human defi-dency states have not been observed, so pantothenic add is presumably present in suffident quantity in all diets. 

Basal data for the HPLC-fluorimetric method for pantothenic add determination. DTMA dodecyltrimethylammonium. 

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