Adenosine diphosphate , enzyme

A good example of an affinity label for creatine kinase has been presented (35). This enzyme catalyzes the reversible transfer of a phosphoryl group from adenosine triphosphate [56-65-5] (17) to creatine [57-00-1] (18), leading to adenosine diphosphate [7584-99-8] (19) and phosphocreatine [67-07-2]... 

Berthold CL, P Moussatche, NGJ Richards, Y Lindqvist (2005) Structural basis for activation of the thiamin diphosphate-dependent enzyme oxalyl-CoA decarboxylase by adenosine diphosphate. J Biol Chem 280 41645-41654. 

Brain hexokinase is inhibited by its product glucose-6-phosphate and to a lesser extent by adenosine diphosphate. The isoenzyme of hexokinase found in brain may be soluble in the cytosol or be attached firmly to mitochondria [2 and references therein]. An equilibrium exists between the soluble and the bound enzyme. The binding changes the kinetic properties of hexokinase and its inhibition by Glc-6-P resulting in a more active enzyme. The extent of binding is inversely related to the ATP ADP ratio, i.e. conditions in which energy utilization... 

Similarly, specific catalysts called enzymes are important factors in determining what reactions occur at an appreciable rate in biological systems. For example, adenosine triphosphate is thermodynamically unstable in aqueous solution with respect to hydrolysis to adenosine diphosphate and inorganic phosphate. Yet this reaction proceeds very slowly in the absence of the specific enzyme adenosine triphosphatase. This combination of thermodynamic control of direction and enzyme control of rate makes possible the finely balanced system that is a hving cell. 

Certain bacterial exntoxins are enzymes that attach the adenosine diphosphate (ADP)-ribose residue of NAD to Ga subunits, an activity known as ADP-ribosylation ... 

In the preceding sections the conversion of purines and purine nucleosides to purine nucleoside monophosphates has been discussed. The monophosphates of adenosine and guanosine must be converted to their di- and triphosphates for polymerization to RNA, for reduction to 2 -deoxyribonucleoside diphosphates, and for the many other reactions in which they take part. Adenosine triphosphate is produced by oxidative phosphorylation and by transfer of phosphate from 1,3-diphosphoglycerate and phosphopyruvate to adenosine diphosphate. A series of transphosphorylations distributes phosphate from adenosine triphosphate to all of the other nucleotides. Two classes of enzymes, termed nucleoside mono-phosphokinases and nucleoside diphosphokinases, catalyse the formation of the nucleoside di- and triphosphates by the transfer of the terminal phosphoryl group from adenosine triphosphate. Muscle adenylate kinase (myokinase)... 

During the past 15 years data from experiments with different types of animal tissues and micro-organisms, using intact cells, crude extracts or purified enzymes, have firmly established the general occurrence of nucleotide reductases and have stressed their importance for DNA synthesis in essentially all types of rapidly growing cells [54]. It has been proposed that ribonucleotide diphosphates lose a hydroxide ion from C-2 to form a carbonium ion which is then stero-specifically reduced by a hydride ion derived from thioredoxin [54]. Adenosine diphosphate and guanosine diphosphate (as well as uridine and cytidine diphosphates) are reduced in this manner. 

The section of the molecule discussed so far represents a functional unit. In the cell, it is produced from pantothenate. The molecule also occurs in a protein-bound form as 4 -phosphopantetheine in the enzyme fatty acid synthase (see p. 168). In coenzyme A, however, it is bound to 3, 5 -adenosine diphosphate. 

The sirtuins (silent information regulator 2-related proteins class III HDACs) form a specific class of histone deacetylases. First, they do not share any sequence or structural homology with the other HDACs. Second, they do not require zinc for activity, but rather use the oxidized form of nicotinamide adenine dinucleotide (NAD ) as cofactor. The reaction catalyzed by these enzymes is the conversion of histones acetylated at specific lysine residues into deacetylated histones, the other products of the reaction being nicotinamide and the metabolite 2 -0-acetyl-adenosine diphosphate ribose (OAADPR) [51, 52]. As HATs and other HDACs, sirtuins not only use acetylated histones as substrates but can also deacetylate other proteins. Intriguingly, some sirtuins do not display any deacetylase activity but act as ADP-ribosyl transferases. 

This enzyme [EC 2.7.7.28], also known as NDP-hexose pyrophosphorylase, catalyzes the reaction of a nucleoside triphosphate with a hexose 1-phosphate to produce a NDP-hexose and pyrophosphate (or, diphosphate). In the reverse reaction the NDP-hexose can be, in decreasing order of activity, guanosine, inosine, and adenosine diphosphate hexoses in which the sugar is either glucose or mannose. 

This enzyme [EC 2.4.2.30] (also referred to as NAD+ ADP-ribosyltransferase, poly(ADP) polymerase, poly-(adenosine diphosphate ribose) polymerase, and ADP-ribosyltransferase (polymerizing)) catalyzes the reaction of NAD+ with [ADP-D-ribosyl] to produce nicotinamide and [ADP-D-ribosyl]( + i). The ADP-d-ribosyl group of NAD+ is transferred to an acceptor carboxyl group on a histone or on the enzyme itself, and further ADP-ribosyl groups are transferred to the 2 -position of the terminal adenosine moiety, building up a polymer with an average chain length of twenty to thirty units. 

Creatine phosphokinase activity has been reported to be minimally inhibited by hemolysis. Hemoglobin concentrations of 1.25 g/100 ml inhibit 5% and 2.5 g/100 ml, 12% (N5). However, in methods utilizing adenosine diphosphate in the reaction mixture, hemolysates containing 100 mg of hemoglobin per 100 ml may have apparent activities of 5-100 units/liter. The activity is presumably related to adenylate kinase in the erythrocyte (S33). In methods utilizing adenosine diphosphate in a coupled enzyme reaction with hexokinase and glucose-6-phosphatase, the inhibitory effect can be eliminated by adding sufficient adenosine mono-... 

The enzymic digestion of an adenosine diphosphate sugar fraction from larch wood leads, among other monosaccharide products, to a fructose.20 This result suggests the occurrence of a corresponding fructosyl ester, but its structure remains undetermined. 

The hydrolysis of adenosine triphosphate 14, ATP, to adenosine diphosphate 15,ADP,is of considerable chemical and biochemical importance since such processes catalyzed by numerous enzymes play a crucial role in... 

Falke, D. Labenz, J. Brauer, D. Muller, W.E.G. Adenosine diphosphate thymidine 5-phosphotransferase, a new enzyme activity, associated with the Herpes simplex virus-induced deoxypyrimidine kinase. Biochim. Biophys. Acta, 708, 99-103 (1982)... 

In another important class of regulatory enzymes, activity is modulated by covalent modification of the enzyme molecule. Modifying groups include phosphoryl, adenylyl, uridylyl, methyl, and adenosine diphosphate ribosyl groups (Fig. 6-30). These groups are generally linked to and removed from the regulatory enzyme by separate enzymes. 

AMP aminohydrolase, an enzyme relatively specific for AMP, has been observed in reptiles (44), erythrocytes (38), snail (45), unfertilized fish eggs (46), invertebrates (47), a variety of mammalian tissues (20), and a particulate fraction of pea seeds (48). Evidence suggests that the frog muscle AMP aminohydrolase is located within or just beneath the sarcolemma (49). The rabbit skeletal and heart muscle enzymes were found in the cytoplasm and mitochondria (20, Jfi, 50, 51), while the enzyme of kidneys and gills of freshwater fish was located in the cytoplasmic fraction (52). The enzyme occurs in most areas of the rat (53) and rabbit brain (54). The nonspecific enzyme from several microbial sources deaminates adenosine triphosphate (ATP) and adenosine diphosphate (ADP) as well as AMP (see Section V). 

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