262863-44-5Relevant academic research and scientific papers
Structure-activity relationships of pyridoxal phosphate derivatives as potent and selective antagonists of P2X1 receptors
Kim,Brown,Harden,Boyer,Dubyak,King,Burnstock,Jacobson
, p. 340 - 349 (2001)
Novel analogues of the P2 receptor antagonist pyridoxal-5′-phosphate 6-azophenyl-2′,5′ disulfonate (2) were synthesized and studied as antagonists in functional assays at recombinant rat P2X1, P2X2, and P2X3 receptors expressed in Xenopus oocytes (ion flux stimulation) and at turkey erythrocyte P2Y1 receptors (phospholipase C activation). Selected compounds were also evaluated as antagonists of ion flux and the opening of a large pore at the recombinant human P2X7 receptor. Modifications were made in the 4-aldehyde and 5′-phosphate groups of the pyridoxal moiety: i.e. a CH2OH group at the 4-position in pyridoxine was either condensed as a cyclic phosphate or phosphorylated separately to form a bisphosphate, which reduced potency at P2 receptors. 5-Methylphosphonate substitution, anticipated to increase stability to hydrolysis, preserved P2 receptor potency. At the 6-position, halo, carboxylate, sulfonate, and phosphonate variations made on the phenylazo ring modulated potency at P2 receptors. The p-carboxyphenylazo analogue, 4, of phosphate 2 displayed an IC50 value of 9 nM at recombinant P2X1 receptors and was 1300-, 16-, and > 10000-fold selective for P2X1 versus P2X2, P2X3, and P2Y1 subtypes, respectively. The corresponding 5-methylphosphonate was equipotent at P2X1 receptors. The 5-methylphosphonate analogue containing a 6-[3,5-bis(methylphosphonate)]phenylazo moiety, 9, had IC50 values of 11 and 25 nM at recombinant P2X1 and P2X3 receptors, respectively. The analogue containing a phenylazo 4-phosphonate group, 11, was also very potent at both P2X1 and P2X3 receptors. However, the corresponding 2,5-disulfonate analogue, 10, was 28-fold selective for P2X1 versus P2X3 receptors. None of the analogues were more potent at P2X7 and P2Y1 receptors than 2, which acted in the micromolar range at these two subtypes.
Arginine- and lysine-specific polymers for protein recognition and immobilization
Renner, Christian,Piehler, Jacob,Schrader, Thomas
, p. 620 - 628 (2007/10/03)
Free radical polymerization of methacrylamide-based bisphosphonates turns weak arginine binders into powerful polymeric protein receptors. Dansyl-labeled homo- and copolymers with excellent water solubility are accessible through a simple copolymerization protocol. Modeling studies point to a striking structural difference between the stiff rodlike densely packed homopolymer 1 and the flexible copolymer 2 with spatially separated bisphosphonate units. Fluorescence titrations in buffered aqueous solution (pH = 7.0) confirm the superior affinity of the homopolymer toward oligoarginine peptides reaching nanomolar KD values for the Tat peptide. Basic proteins are bound almost equally well by 1 and 2 with micromolar affinities, with the latter producing much more soluble complexes. The Arg selectivity of the monomer is transferred to the polymer, which binds Arg-rich proteins 1 order of magnitude tighter than lysine-rich pendants of comparable pl, size, and (Arg/Lys vs Glu/Asp) ratio. Noncovalent deposition of both polymers on glass substrates via polyethyleneimine layers results in new materials suitable for peptide and protein immobilization. RlfS measurements allow calculation of association constants Ka as well as dissociation kinetics kD. They generally confirm the trends already found in free solution. Close inspection of electrostatic potential surfaces suggest that basic domains favor protein binding on the flat surface. The high specificity of the bisphosphonate polymers toward basic proteins is demonstrated by comparison with polyvinyl sulfate, which has almost no effect in RlfS experiments. Thus, copolymerization of few different comonomer units without cross-linking enables surface recognition of basic proteins in free solution as well as their effective immobilization on surfaces.
Optimization of a synthetic arginine receptor. Systematic tuning of noncovalent interactions
Rensing,Arendt,Springer,Grawe,Schrader
, p. 5814 - 5821 (2007/10/03)
The simple arginine binder 1 could be optimized by strengthening π-cation as well as electrostatic interactions. Electron-donating or -withdrawing substituents in the 5-position provide experimental evidence for π-cation interactions, because binding energies increase by up to 0.6 kcal/mol due to a single benzene-guanidinium interaction. Even more effective is the introduction of a third phosphonate functionality at the correct distance, so that the guanidinium cation is recognized by optimal electrostatic and hydrogen bond interactions. Monte Carlo simulations and NOESY experiments confirm the expected complex geometries. The optimized host molecule 8 binds arginine half an order of magnitude more efficiently than the parent molecule.
Acyclic analogues of deoxyadenosine 3',5'-bisphosphates as P2Y1 receptor antagonists
Kim, Yong-Chul,Gallo-Rodriguez, Carola,Jang, Soo-Yeon,Nandanan, Erathodiyil,Adams, Mary,Harden, T. Kendall,Boyer, José L.,Jacobson, Kenneth A.
, p. 746 - 755 (2007/10/03)
P2Y1 receptors are activated by ADP and occur on endothelial cells, smooth muscle, epithelial cells, lungs, pancreas, platelets, and in the central nervous system. With the aid of molecular modeling, we have designed nucleotide analogues that act as selective antagonists at this subtype. The present study has tested the hypothesis that acyclic modifications of the ribose ring, proven highly successful for nucleoside antiviral agents such as gancyclovir, are generalizable to P2Y receptor ligands. Specifically, the binding site of the P2Y1 receptor was found to be sufficiently accommodating to allow the substitution of the ribose group with acyclic aliphatic and aromatic chains attached to the 9-position of adenine. Three groups of adenine derivatives having diverse side-chain structures, each containing two symmetrical phosphate or phosphonate groups, were prepared. Biological activity was demonstrated by the ability of the acyclic derivatives to act as agonists or antagonists in the stimulation of phospholipase C in turkey erythrocyte membranes. An acyclic N6-methyladenine derivative, 2-[2-(6- methylaminopurin-9-yl)-ethyl]-propane-1,3-bisoxy(diammoniumphosphate) (10), containing an isopentyl bisphosphate moiety, was a full antagonist at the P2Y1 receptor with an IC50 value of 1.60 μM. The corresponding 2-Cl derivative (11) was even more potent with an IC50 value of 0.84 μM. Homologation of the ethylene group at the 9-position to 3-5 methylene units or inclusion of cis- or trans-olefinic groups greatly reduced antagonist potency at the P2Y1 receptor. Analogues containing a diethanolamine amide group and an aryl di(methylphosphonate) were both less potent than 10 as antagonists, with IC50 values of 14 and 16 μM, respectively, and no agonist activity was observed for these analogues. Thus, the ribose moiety is clearly not essential for recognition by the turkey P2Y1 receptor, although a cyclic structure appears to be important for receptor activation, and the acyclic approach to the design of P2 receptor antagonists is valid.
