- THE QUEEN RECOGNITION PHEROMONE OF SOLENOPSIS INVICTA, PREPARATION OF (E)-6-(1-PENTENYL)-2H-PYRAN-2-ONE.
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The title compound, I, prepared in five steps via four known α-pyrones, is responsible, in part, for "queen recognition" by red imported fire ant workers.IR, NMR and MS data are presented.
- Rocca, J. R.,Tumlinson, J. H.,Glancey, B. M.,Lofgren, C. S.
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- A designed synthetic analogue of 4-OT is specific for a non-natural substrate
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The substrate specificity of 4-oxalocrotonate tautomerase (4-OT) is characterized by electrostatic interactions between positively charged arginine (Arg) side chains on the enzyme and the dianionic substrate, 4-oxalocrotonate. To generate specific hydrogen-bonding interactions with a monoanionic substrate analogue, we have introduced a urea functional group into the active site by replacing arginine side chains with isosteric citrulline (Cit) residues. This design was based on the complementarity between the urea functionality of citrulline and the uncharged amide function of the substrate, as opposed to the guanidinium-carboxylate electrostatic interaction between the wild-type enzyme and the natural substrate. Indeed, the synthetic (Arg39Cit)4-OT analogue catalyzed the tautomerization of the non-natural monoamide-monoacid substrate while it was a poor catalyst for the natural diacid substrate. The specificity of (Arg39Cit)4-OT for the monoamide-monoacid substrate relative to that of the diacid substrate was found to be 740-fold greater than that of the wild-type enzyme for tautomerization of the non-natural substrate as compared with the natural one. The role of electrostatic interactions in the tautomerization of the monoamide-monoacid substrate was probed in detail with several other Arg to Cit analogues of this enzyme. This study has demonstrated that chemical manipulation of the functional groups within the active site of an enzyme can modify its catalytic activity and substrate specificity in a predictable way, suggesting that the incorporation of noncoded amino acids into proteins has great promise for the development of new enzymatic mechanisms and new binding interactions.
- Metanis, Norman,Keinan, Ehud,Dawson, Philip E.
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- Ruthenium-catalyzed dimerization of propiolates: A simple route to α-pyrones
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A ruthenium-catalyzed regioselective intermolecular multistep homo- and heterodimerization of substituted propiolates providing α-pyrone-5- carboxylates and α-pyrone-6-carboxylates is described. The synthetic utilities of α-pyrone derivatives are shown. The proposed mechanism is strongly supported by experimental evidence.
- Manikandan, Rajendran,Jeganmohan, Masilamani
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p. 652 - 655
(2014/03/21)
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- COSMETIC OR DERMATOLOGICAL COMPOSITION COMPRISING A POLYMER BEARING JUNCTION GROUPS, AND COSMETIC TREATMENT PROCESS
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The present patent application relates to a cosmetic or dermatological composition comprising, in a cosmetically or dermatologically acceptable medium, a polymer comprising: (a) a polymer backbone that may be obtained by reaction: of a polyol comprising 3 to 6 hydroxyl groups;of a monocarboxylic acid containing 6 to 32 carbon atoms;of a polycarboxylic acid comprising at least two carboxylic groups COOH, and/or of a cyclic anhydride such as a polycarboxylic acid and/or of a lactone comprising at least one carboxylic group COOH; and(b) at least one junction group linked to the said polymer backbone and capable of establishing H bonds with one or more partner junction groups, each pairing of a junction group involving at least three H (hydrogen) bonds. The patent application also concerns a cosmetic treatment process using the said composition.
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- NOVEL PYRONE-INDOLE DERIVATIVES AND PROCESS FOR THEIR PREPARATION
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The present invention relates to novel pyrone-indole derivatives, pharmaceutical formulations containing them, and use of the compounds in the manufacture of Medicaments for treating or preventing various diseases.
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Page/Page column 37; 38
(2010/11/28)
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