Adenylyl imidodiphosphate

Lasek, R. J. and Brady, S. T. Adenylyl imidodiphosphate (AMPPNP), a nonhydrolyzable analogue of ATP, produces a stable intermediate in the motility cycle of fast axonal transport. Biol. Bull. 167 503,1984. 

The ATP-regenerating system may complicate the analysis because of its possible influence on the adenylate cyclase activity. For example, 5 -adenylyl imidodiphosphate (AMP-PNP) labelled with a- P, an analogue of ATP containing Nitrogen substituted for Oxygen between the terminal phosphates, has been used to circumvent the problems encountered in maintaining the substrate concentration during kinetic studies of adenylate cyclase activity [109]. AMP-PNP is a substrate for adenylate cyclase and is only slowly hydrolysed by ATPase. Unlabelled AMP-PNP... 

In the continuing search for isozyme-specific inhibitors of rat methionine adenosyltransferases, the covalent conjugate (119) of L-ethionine and adenylyl imidodiphosphate has been prepared. 23 in the synthetic route, protected adenosine was converted to its 5 -aldehyde, condensed with vinylmagnesium bromide, and hydroboration, tosylation and condensation with L-homocysteinate served to introduce the L-ethionine moiety, the 5 -hydroxy group then being phosphorylated by Tener s method and converted conventionally to the p, y-imidotriphosphate. 

A resolution). AMPPNP (5 -adenylyl imidodiphosphate) is a nonhydrolyzable analog of ATP, which traps the transporter in the closed state. The apo state of the transporter is defined by a V-shaped chamber open to the cytoplasm and the inner leaflet of the membrane, with the two NBDs separated by about 5 nm (Fig. 4a). Addition of AMPPNP induces a tight packing of the NBDs which sandwiches the two nucleotides and induces an opening of the TMDs towards the outer leaflet of the bilayer. 

Van de Ven et al. [75] have, therefore, used the non-hydrolysable analogue adenylyl imidodiphosphate (AMPPNP) as a substitute for ATP and have measured the binding characteristics of this compound. A dissociation constant of 53 jaM was obtained and the maximal AMPPNP binding was 2.8 nmol/mg protein. The amount of binding was decreased by monovalent cations in the same order of potency as for... 

Measurement of adenyl cyclase activity was a laborious and imprecise procedure until the introduction of the method of Krishna et al. This method is based on the production of labeled cyclic AMP from ATP-a- P. Labeled product is separated from substrate by a combination of ion exchange chromatography and adsorption of substrate to nascent BaS04 precipitate. With appropriate equipment, it is possible to perform 300 adenyl cyclase assays in one day. A complication of the method arises from the fact that adenyl cyclase preparations invariably contain sufficient ATPase activity to deplete rapidly the substrate concentration, thereby shortening the period of time over which adenyl cyclase activity can be observed and precluding even the simplest kinetic analysis. This problem has generally been overcome by addition of an ATP-regenerating system to the adenyl cyclase assay medium . In addition, it has recently been shown that 5 -adenylyl-imidodiphosphate (AMP-PNP) is a substrate for adenyl cyclase but not for ATPase ... 

Kinesin a soluble protein isolated from the axoplasm of squid giant axons apparent M, 600,000. In the presence of the non-hydrolysable ATP analog, adenylyl imidodiphosphate, it binds tightly to microtubules, but it is released from them by ATP. K. apparently consists of subunits of M, 110,000, 70,000 and 65,000. Polypeptides from bovine brain with similar binding properties and M, 120,000 and 62,000 have also been isolated. In the presence of ATP, K. causes... 

Abbreviations DAMN-cymarin, 4 -(ethyldiazomalonly)cymarin CM-cymarin, 4 -(ethylchloromalonyl)cymarin AMPPNP, adenylyl imidodiphosphate. 

Inhibition of Mitochondrial Fj-ATPase by Adenylyl Imidodiphosphate Michael J. Gresser, Seelochan Beharry, and Denise M. C. Moennich... 

Phosphorylase kinase, one of the Ser/Thr-kinases, is oligomeric with the stoichiometry (a/3yS)4.80> The y-subunit of the enzyme is homologous to other protein kinases and possesses protein kinase activity when separated from other subunits.811 Phosphorylase kinase was more effectively inactivated by AP3-PL and AP4-PL than PLP and AP2-PL. Ca2+ and Mg2+, activators for this enzyme, enhanced the degree of inactivation by all the pyridoxal compounds. Inactivation by AP3-PL and AP4-PL was markedly protected by adenylyl, /3,y-imidodiphosphate, a nonhydrolyzable analogue of ATP, and ADP. Because the a- and /3-subunits have regulatory ATP-binding sites and the kinase activity is regulated by these subunits,821 the incorporation of AP3-PL into the y-subunit and... 

Absorption, distribution, metabolism, elimination 5 -adenylyl /1-y-imidodiphosphate Aminohexanoic acid Adenosine monophosphate Apolipoprotein D... 

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