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Carboxylic acids, 5 -adenylic acid

A.7.1 Esterification of Acids using Carbodiimides. The formation of anhydrides from carboxylic acids, thiocarboxylic acids, sulfonic acids and phosphorous acids are discussed in Section 2.4.S.2. In this section only special cases of anhydride formation are described. Mixed anhydrides of amino acids and adenylic acid are produced from the corresponding acids using DCC as the condensation agent. ° Mixed anhydrides not containing amino acids, such as butyryl adenate, adenosine 5 -phosphosulfate and p-nitrophenyl-thymidine-5-phosphate are also obtained. [Pg.113]

In fatty-acid biosynthesis, a carboxylic acid is activated by reaction with ATP to give an acyl adenylate, which undergoes nucleophilic acyi substitution with the — SH group or coenzyme A. (ATP = adenosine triphosphate AMP = adenosine monophosphate.)... [Pg.801]

The structure of firefly luciferin has been confirmed by total synthesis. The firefly emits a ycllow-grccn luminescence, and luciferin in this case is a benzthiazole derivative. Activation of the firefly luciferin involves the elimination of pyrophosphate from ATP widi the formation of an add anhydride linkage between the carboxyl group of luciferin and the phosphate group of adenylic acid forming luciferyl-adenylate. [Pg.203]

An early emergence of adenylate-forming enzymes can also explain the wide diversification of this family of enzymes [175], many of which are now capable of reacting with carboxylic acids without a-amino group (essential in the hypothetical early mechanism using NCAs as substrates, but then useless) and which is involved in many different biosynthetic pathways. [Pg.112]

In firefly luciferase reaction, the luminescence activity is enhanced by addition of Coenzyme A (CoA) and this phenomenon is explained by release of product inhibition. Also, firefly luciferase shows the sequence similarity to mammalian fatty acyl-CoA synthetase (AcCoAS) and plant 4-coumarate CoA ligase (4CL). They are classified as an adenylation enzyme for synthesizing acyl-CoA derivatives fi om carboxylic acid compounds in the presence of CoA, ATP and Mg (Scheme 1). Furthermore, it was reported that the luminescence activity of firefly luciferase is inhibited competitively by various long-chain fatty acids. We have determined that firefly luciferase is a bi-functional enzyme, catalyzing both the luminescence reaction and fatty acyl-CoA synthetic reaction. ... [Pg.53]

One way living organisms activate carboxylic acids is to convert them into acyl phosphates, acyl pyrophosphates, and acyl adenylates. [Pg.713]

An acyl phosphate is a mixed anhydride of a carboxylic acid and phosphoric acid an acyl pyrophosphate is a mixed anhydride of a carboxylic acid and pyrophosphoric acid an acyl adenylate is a mixed anhydride of a carboxylic acid and adenosine monophosphate (AMP). [Pg.713]

The first step in converting a carboxylic acid into a thioester is to convert the carboxylic acid into an acyl adenylate. The acyl adenylate then reacts with CoASH to form the thioester. The most common thioester in cells is acetyl-CoA. [Pg.715]

In Section 17.20 we saw that carboxylic acids in biological systems can be activated by being converted into acyl phosphates, acyl pyrophosphates, and acyl adenylates. Each of these three mechanisms puts a leaving group on the carboxylic acid that can easily be displaced by a nucleophile. The only difference in the three mechanisms is the particular phosphate atom that is attacked by the nucleophile and the nature of the intermediate that is formed. [Pg.1114]

Biochemical analyses of the assembly of the ergopeptines in C. purpurea have shown that ergopeptines are the products of an enzyme complex consisting of two nonribosomal peptide synthetase (NRPS) subunits (55). NRPSs generally exhibit modular structures, with each module responsible for the addition of an amino acid or other substituent. A typical module includes an adenylation (A-) domain, a thiolation (T-) domain (also known as a peptidyl carrier protein domain), and a condensation (C-) domain. The A-domain specifies the amino acid or other carboxylic acid substituent, and activates by it by an ATP-dependent adenylation reaction. The activated substituent then forms a thioester with the 4 -phosphopan-tetheine prosthetic group in the adjacent T-domain. Finally, the C-domain links the substituent to the next substituent in the chain. In a multimodular NRPS protein, the order in which substituents are added corresponds to the arrangement of modules from its N- to C terminus. [Pg.67]

The direct route of acyl coenzyme A synthesis from a free carboxylic acid is catalysed by a group of nucleoside triphosphate-requiring en mes, collectively known as thiokinases. The general mechanism, as exemplified for acetate activation by acetyl thiokinase, proceeds as follows. The carboxylic acid is first activated by acetyl adenylate formation with the displacement of pyrophosphate from ATP. While the initial reaction is fully reversible, subsequent action of pyrophosphatase drives the reaction... [Pg.325]

Because the nature of the bond fonnalion process is different in PKs and NRPs (Claisen condensations vs. peptide bond formalion), NRPSs necessarily utilize different domains. Specifically, the three essential domains of the NRPS are an adenylation (A), peptide carrier protein (PCP), and condensation (C) domain. NRP biosynthesis begins with activation of the amino add through adenylation of the carboxylic acid group by the A domain, a process facilitated by the presence of Mg +. In the adenylation reaction, ATP reacts with the selected amino acid to form the activated phosphoester aminoacyl adenylate and pyrophosphate (Figure 4.10a). The A domain is also a key point of selectivity during NRP biosynthesis as it is responsible for the selection of the particular amino acid to be activated. [Pg.79]

Acylation of peptides by aliphatic or aromatic carboxylic acids is followed by different routes. The respective carboxylic acids are supplied by linked ptolyke-tide synthases, either of the fatty acid or various polyketide synthase types, and introduced as either CoA esters or activated directly as adenylates. Several such activating systems have been characterized (see Section III.A.5). To initiate peptide synthesis with CoA esters, respective transferases arc required ... [Pg.231]

The S. chrysormllus enzyme displays dififerent activities in the presence of a number of different benzene carboxylic acids tested as substrates (Table 2). The value of the equilibrium constant of the adenylate formation reaction, was increased when substituents such as an amino-, hydroxyl-, or methyl-groups in the 4-position were present, compared with benzoic acid alone. The same substituents in the 3-position resulted in a less pronounced response of the enzyme, whereas substituents in the Z-position were... [Pg.339]

Adenosine triphosphate disodium, A-39 Adenosine triphosphate, A-39 Adenosine 5 -triphosphoric acid, A-39 Adenosine 5 -uridine 5 -phosphate, A-40 Adenosine 5 -[4-(fluorosulfonyl)benzoate], F-17 Adenosine, A-31 e-Adenosine, R-110 a-Adenosine, A-31 Adenosine-5 -carboxamide, A-41 Adenosine-5 -carboxylic acid, A-41 Adenosine-5 -diphosphoric acid, A-33 Adenosine-5 -N-ethyluronamide, A-41 Adenosine-5 -phosphoric acid, A-44 Adenosine-2 -phosphoric acid, A-45 Adenosine-5 -uronic acid, A-41 S -Adenosylhomocysteine, A-42 S -Adenosylmethionine, A-26 Adenosylsuccinic acid, A-43 Adenylic acid a, A-45... [Pg.994]


See other pages where Carboxylic acids, 5 -adenylic acid is mentioned: [Pg.800]    [Pg.817]    [Pg.1282]    [Pg.427]    [Pg.640]    [Pg.635]    [Pg.507]    [Pg.1341]    [Pg.16]    [Pg.300]    [Pg.302]    [Pg.800]    [Pg.119]    [Pg.507]    [Pg.800]    [Pg.817]    [Pg.156]    [Pg.431]    [Pg.382]    [Pg.212]    [Pg.428]    [Pg.819]    [Pg.407]    [Pg.435]    [Pg.230]    [Pg.339]    [Pg.407]    [Pg.293]   


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Acyl adenylate, from carboxylic acids

Acyl adenylate, from carboxylic acids mechanism of formation

Adenylate

Adenylation

Adenylic acid

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