Adenosine triphosphate, amino group

The most common example of this process in living organisms is the reaction of the amino acid methionine with adenosine triphosphate (ATP Section 5.8) to give S-adenosylmethionine. The reaction is somewhat unusual in that the biological leaving group in this SN2 process is the triphosphate ion rather than the more frequently seen rliphosphate ion (Section 11.6). 

For most amino acids, the ester linkage between the ct-COOH group of the amino acid and the 3 -terminal adenosine of a cognate tRNA is formed in a two-step mechanism catalyzed by an aminoacyl-tRNA synthetase (aaRS). ° In this so-called direct pathway, the aaRS first catalyzes the reaction of the amino acid with adenosine triphosphate (ATP), yielding the enzyme-bound high-energy intermediate aa AMP and PPi in the second step, this aaRS-bound intermediate reacts with tRNA to yield aa-tRNA and AMP (Figure 1). 

Adenosine deaminase (ADA) is a ubiquitous enzyme that is essential for the breakdown of the purine base adenosine, from both food intake and the turnover of nucleic acids. ADA hydrolyzes adenosine and deoxyadenosine into inosine and deoxyinosine, respectively, via the removal of an amino group. Deficiency of the ADA enzyme results in the build-up of deoxyadenosine and deoxyATP (adenosine triphosphate), both of which inhibit the normal maturation and survival of lymphocytes. Most importantly, these metabolites affect the ability of T-cells to differentiate into mature T-cells [656430], [666686]. ADA deficiency results in a form of severe combined immunodeficiency (SCID), known as ADA-SCID [467343]. 

Firefly luciferase catalyzes the reaction of adenosine triphosphate and a substituted benzothiazole luciferin. The quantum yield of the reaction is high and therefore measurement of the enzyme offers good sensitivity. Coupling of luciferase to other molecules is a problem because there is a highly reactive amino group in the active site that must be protected from reaction with coupling rei ents (36, 37). 

The application of LSR to amino-acids has received some attention. (451-456, 498) Such studies are an essential preliminary to the use of LSR for amino-acid sequence determination in simple peptides and proteins. The latter are discussed more comprehensively in Section G. A detailed study has been made (453) of the interaction of Eu(iii), Pr(iii), Gd(iii), and La(iii) with iV-acetyl-L-3-nitrotyrosine in order to characterize the nitrotyrosine residue as a potential specific lanthanide binding site in proteins. The parameters of the dipolar interaction indicate a significant contribution from non axially symmetric terms. The conformations of the nucleotides cyclic j8-adenosine 3, 5 -phosphate (3, 5 -AMP) (457, 458) and adenosine triphosphate (ATP) (459) have been deduced using LSR. In the former case the conformation of the ribose and phosphate groups is consistent with the solid state structure. A combination of lanthanide shift and relaxation reagents was used to deduce the most favoured family of conformations for ATP in aqueous solution. One of these conformations corresponds closely to one of the crystal structure forms. 

In general, mechanisms for the biosynthesis of polyamides can be divided into three different pathways, which mainly differ in the mode of activation of the monomers (adenylation or phosphorylation), the dependency on a template, and the enzyme apparatus. In comparison to the activation by phosphorylation, adenylation involves synthesis of a phosphodiester bond between the hydroxyl group of the carboxylic group of the amino acid and the a-phosphate group of adenosine triphosphate (ATP). Activation by phosphorylation has been proposed that is, for synthesis of the tripeptide glutathione (Gly-Glu-Cys) or transpeptidase, the... 

Amino acid decarboxylase Classic autism Asperger s syndrome Adenosine-triphosphate Childhood disintegrative disorder Central nervous system Carboxyl group... 

Protein tyrosine kinases are enzymes that catalyze the transfer of phosphate from adenosine triphosphate (ATP) to the hydroxyl group of the amino acid tyrosine on many essential proteins. These proteins play an essential role in cell signalling, regulation of cell growth and transformation of the cells [10]. The identification of specific inhibitors of protein tyrosine kinase may uncover potential anticancer agents [10]. Jayatilak et al. [60] investigated the kinase inhibitor activity of stilbene compounds, 15-20, that were extracted from the polar methanol fraction of Polygonum cuspidatum roots. The compounds were evaluated in protein... 

SAM is synthesized by the transfer of an adenosyl group from adenosine triphosphate (ATP) to the sulfur atom of the amino acid methionine. The positive charge on the sulfur atom activates the methyl group of methionine, making SAM a potent methyl carbonium ion (Me ) donor. SAM is considered a ubiquitous methylating agent. 

Compounds structurally related to adenosine 5 -triphosphate also exhibit inhibition. Among adenosine 5 -pyrophosphate, adenosine 5 -phos-phate, adenosine, and adenine, adenosine showed the strongest inhibition. This result indicated that the adenine and n-ribose moieties of adenosine 5 -triphosphate bind with the enzyme. Formycin A is an analog of adenosine, and exhibits inhibition (61% at 3.2 mM) formycin B is less active. This suggested that the amino group of adenosine binds with the... 

Nonribosomal peptide synthesis means that the peptide is not produced by the tRNA-mRNA mechanism described in Chapter 28, Section 28.6. Each amino acid found in 224 is directly selected for incorporation into the growing peptide chain by one of the domains of surfactin synthetase, shown with the pendant SH groups. Substrate activation occurs after binding the amino acid, and the enzyme catalyzes the formation of an aminoacyl adenylate intermediate using Mg2+-ATP and release of a cofactor. Subsequently, the amino acid-O-AMP oxoester is converted into a thioester by a nucleophilic attack of the free thiol-bound cofactor of an adjacent PCP domain. (Note that ATP is adenosine triphosphate and AMP is adenosine monophosphate see Chapter 28, Section 28.5.)... 

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