Structure coenzyme A

Codon (mRNA), 1109-1110 table of, 1110 Coenzyme, 162, 1042 table of, 1044-1045 Coenzyme A, structure of, 817, 1044 Coenzyme Q, 632 Cofactor (enzyme), 1042 Color, perception of, 503-504 UV spectroscopy and. 503-505 Combinatorial chemistry, 586-587 kinds of, 586... 

In 1940, Hams, Folkers, ct al. reported structure determination and synthesis and crystallization of pantothenic acid. In 1950. Lipmaiin el al. discovered coenzyme A and, in 1951, Lynen characterized the coenzyme A structure,... 

The malonic ester synthesis might seem like an arcane technique that only an organic chemist would use. Still, it is much like the method that cells use to synthesize the long-chain fatty acids found in fats, oils, waxes, and cell membranes. Figure 22-4 outlines the steps that take place in the lengthening of a fatty acid chain by two carbon atoms at a time. The growing acid derivative (acyl-CoA) is activated as its thioester with coenzyme A (structure on page 1027). A malonic ester acylation adds two of the three carbons of malonic acid (as malonyl-CoA), with the third carbon lost in the decarboxylation. A )8-ketoester results. Reduction of the ketone, followed by dehydration and reduction of... 

Pantothenic acid, also known as vitamin B5, is widely distributed in food, since it is a component in the coenzyme A structure. Therefore, it is essential to all organisms and its deficiency is imcommon. In addition, being part of this coenzyme, for the total vitamin B5 determination, an enzyme hydrolysis is necessary prior to analysis. Foods richest in pantothenic acid are organ meats, egg yolk, and whole grains. RP separations are employed to analyze pantothenic acid, which does not possess any specific UV—Vis absorption. To overcome this problem, either fluorescence detection or MS detection is employed. 

Figure 10.3-19. Representation of the reaction shown fn Figure 10.3-16, indicating all the atoms and bonds of the chemical structures as well as the reaction center. For the sake of clarity, the coenzyme A has been abbreviated.

We can descnbe the major elements of fatty acid biosynthesis by considering the for mation of butanoic acid from two molecules of acetyl coenzyme A The machinery responsible for accomplishing this conversion is a complex of enzymes known as fatty acid synthetase Certain portions of this complex referred to as acyl carrier protein (ACP), bear a side chain that is structurally similar to coenzyme A An important early step m fatty acid biosynthesis is the transfer of the acetyl group from a molecule of acetyl coenzyme A to the sulfhydryl group of acyl carrier protein... 

Using HSCoA and HS—ACP as abbreviations for coenzyme A and acyl carrier protein respectively write a structural formula for the tetrahedral... 

Chemists and biochemists And it convenient to divide the principal organic substances present m cells into four mam groups carbohydrates proteins nucleic acids and lipids Structural differences separate carbo hydrates from proteins and both of these are structurally distinct from nucleic acids Lipids on the other hand are characterized by a physical property their solubility m nonpolar solvents rather than by their structure In this chapter we have examined lipid molecules that share a common biosynthetic origin m that all their carbons are derived from acetic acid (acetate) The form m which acetate occurs m many of these processes is a thioester called acetyl coenzyme A... 

There is one exception to the rule that requires bulky hydrophobic residues to fill the interior of eight-stranded a/p barrels in order to form a tightly packed hydrophobic core. The coenzyme Biz-dependent enzyme methylmalonyl-coenzyme A mutase, the x-ray structure of which was determined by Phil Evans and colleagues at the MRC Laboratory of Molecular... 

Figure 4.4 Schematic diagram of the structure of the a/p-barrel domain of the enzyme methylmalonyl-coenzyme A mutase. Alpha helices are red, and p strands are blue. The inside of the barrel is lined by small hydrophilic side chains (serine and threonine) from the p strands, which creates a hole in the middle where one of the substrate molecules, coenzyme A (green), binds along the axis of the barrel from one end to the other. (Adapted from a computer-generated diagram provided by P. Evans.)...

Several classes of vitamins are related to, or are precursors of, coenzymes that contain adenine nucleotides as part of their structure. These coenzymes include the flavin dinucleotides, the pyridine dinucleotides, and coenzyme A. The adenine nucleotide portion of these coenzymes does not participate actively in the reactions of these coenzymes rather, it enables the proper enzymes to recognize the coenzyme. Specifically, the adenine nucleotide greatly increases both the affinity and the speeifieity of the coenzyme for its site on the enzyme, owing to its numerous sites for hydrogen bonding, and also the hydrophobic and ionic bonding possibilities it brings to the coenzyme structure. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

The sharp flash in the firefly bioluminescence reaction (Fig. 1.6) is due to the formation of a strongly inhibitory byproduct in the reaction. The inhibitor formed is dehydroluciferyl adenylate, having the structure shown below at left. In the presence of coenzyme A (CoA), however, this inhibitory adenylate is converted into dehydroluciferyl-CoA, a compound only weakly inhibitory to luminescence. Thus, an addition of CoA in the reaction medium results in a long-lasting, high level of luminescence (Airth et al., 1958 McElroy and Seliger, 1966 Ford et al., 1995 Fontes et al., 1997, 1998). 

Koenig K, JR Andreesen (1990) Xanthine dehydrogenase and 2-furoyl-coenzyme A dehydrogenase from Pseudomonasputida Ful two molybdenum-containing dehydrogenases of novel structural composition. J Bacterial 172 5999-6009. 

Marita, J. M. Ralph, J. Hatheld, R. D. Guo, D. Chen, F. Dixon, R. A. Structural and compositional modihcations in lignin of transgenic alfalfa down-regulated in caffeic acid 3-O-methyltransferase and caffeoyl coenzyme A 3-O-methyltransferase. 

Following the elucidation of the structure of the biologically active forms of Vitamin B12 in 1961, a number of enzymes have been well characterized which require B 12-coenzymes. A survey of the properties of these enzymes in terms of molecular weight, subunits and other co-factor requirements has already been published in excellent reviews by Hogenkamp (29) and Stadtman (30). 

Kragelund, B.B., Andersen, K.V., Madsen, J.C., Knudsen, J. and Poulsen, F.M. (1993) Three-dimensional structure of the complex between acyl-coenzyme A binding protein and palmitoyl-coenzyme A. Journal of Molecular Biology 230, 1260-1277. 

PHA synthases are the key enzymes of PHA biosynthesis. These enzymes catalyze the covalent linkage between the hydroxyl group of one and the carboxyl group of another hydroxyalkanoic acid. The substrates of PHA synthases are the coenzyme A thioesters of hydroxyalkanoic acids there is no evidence that PHA synthases can utilize either free hydroxyalkanoic acids or other derivatives of hydroxyalkanoic acids. With respect to size, structure, and substrate specificity, three different types of PHA synthases (I, II, and III) can be distinguished (see below). 

Structures of CHS complexed with different Coenzyme A (CoA) thioesters and product analogs (i.e., naringenin and resveratrol) demonstrate that the active site is buried within an interior cavity located in the cleft between the upper and lower domains of each monomer (Fig. 12.3). Considering the complexity of the reaction... 

---