02225nas a2200205 4500008004100000022001400041245012900055210006900184260007100253300001200324490000700336520140500343100002701748700002101775700001901796700002601815700003501841700001701876856012601893 2016 eng d a0022-326300aTuning emission responses of a triphenylamine derivative in host-guest complexes and an unusual dynamic inclusion phenomenon0 aTuning emission responses of a triphenylamine derivative in host a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN a512-5210 v813 a

A newly synthesized triphenylamine derivative (1Cl(3)) shows significant differences in inclusion complex formation with two different macrocyclic hosts, cucurbit[7]uril (CB[7]) and beta-cyclodextrin (beta-CD). Detailed investigations by NMR spectroscopy reveal that CB[7] forms a 1:3 host-guest complex ([1 center dot 3{CB[7]}]Cl-3) in which three arms of 1Cl(3) are bound to three host molecules. On the other hand, beta-CD forms a dynamic 1:1 inclusion complex ([1 center dot{beta-CD}]Cl-3) by binding to only one of the three arms of 1Cl(3) at a given time. The formation of a 1:1 host-guest complex with beta-CD and 1:3 host-guest complex with CB[7] was also confirmed from the results of the isothermal titration calorimetric studies. Interestingly, 1Cl(3) exhibits a rare dual emission property in solution at room temperature with the lower and higher energy bands arising from a locally excited state and an intramolecular charge-transfer transition, respectively. The difference in inclusion complex formation behavior of 1Cl(3) with the two macrocyclic hosts results in the stabilization of different emission states in the two inclusion complexes. The fundamental difference in the electrostatic surface potentials, cavity polarities, and shapes of the two macrocyclic hosts could account for the formation of the different inclusion complexes with distinct luminescence responses.

1 aGangopadhyay, Monalisa1 aMandal, Amal, K.1 aMaity, Arunava1 aRavindranathan, Sapna1 aRajamohanan, Pattuparambil, R.1 aDas, Amitava uhttps://library.ncl.res.in/content/tuning-emission-responses-triphenylamine-derivative-host-guest-complexes-and-unusual-102042nas a2200277 4500008004100000022001100041245009300052210006900145260000800214300001200222490000800234520107600242653004901318653002101367653007401388653001301462653002001475100001701495700001801512700001801530700002101548700002601569700002401595700002501619856012001644 2018 eng d a32386100aThermo thickening behavior of MPEG-b-PCL grafted poly(acrylic acid): a molecular insight0 aThermo thickening behavior of MPEGbPCL grafted polyacrylic acid  cJUL a138-1480 v1483 a

We report on the synthesis and characterization of a new thermothickening polymer (PAA-g-(MPEG-b-PCL)) based on the grafting of a block copolymer of mono methoxy poly (ethylene glycol)–b-poly (caprolactone) (MPEG-b-PCL) onto poly (acrylic acid) (PAA). Rheological experiments reveal that aqueous solutions of PAA-g-(MPEG-b-PCL) exhibit interesting irreversible thermothickening behavior above a certain polymer concentration and critical temperature. Light scattering experiments show that increasing temperature induces hydrophobic associations and subsequent aggregation leading to gel formation which is irreversible. The mechanism of thermo thickening was examined at the molecular level by NMR methods which indicated unassembled and assembled environments of the MPEG-b-PCL grafts. On heating, interactions between the graft side chains are significantly enhanced and molecular mobility in the assembled microdomains is reduced. The stable well ordered microdomains that are formed on heating are retained on cooling thus, leading to irreversible gelation.

10aHydrophobically modified poly (acrylic acid)10aLight scattering10aMethoxy polyethylene glycol-b-polycaprolactone (MPEG-b-PCL) copolymer10aRheology10aThermo gelation1 aTiwari, Neha1 aShedge, Aarti1 aFayis, K., P.1 aBhat, Suresh, K.1 aRavindranathan, Sapna1 aRajamohanan, P., R.1 aBadiger, Manohar, V. uhttps://library.ncl.res.in/content/thermo-thickening-behavior-mpeg-b-pcl-grafted-polyacrylic-acid-molecular-insight02097nas a2200217 4500008004100000022001400041245013700055210006900192260000800261300001400269490000700283520130600290100002201596700002001618700002401638700001801662700001601680700002601696700002601722856013101748 2020 eng d a0305-104800aTransient alpha-helix in the N-terminal RNA recognition motif of polypyrimidine tract binding protein senses RNA secondary structure0 aTransient alphahelix in the Nterminal RNA recognition motif of p cMAY a4521-45370 v483 a

The polypyrimidine tract binding protein (PTB) is a multi-domain protein involved in alternative splicing, mRNA localization, stabilization, polyadenylation and translation initiation from internal ribosome entry sites (IRES). In this latter process, PTB promotes viral translation by interacting extensively with complex structured regions in the 5'-untranslated regions of viral RNAs at pyrimidine-rich targets located in single strand and hairpin regions. To better understand how PTB recognizes structured elements in RNA targets, we solved the solution structure of the N-terminal RNA recognition motif (RRM) in complex with an RNA hairpin embedding the loop sequence UCUUU, which is frequently found in IRESs of the picornovirus family. Surprisingly, a new three-turn alpha 3 helix C-terminal to the RRM, folds upon binding the RNA hairpin. Although alpha 3 does not mediate any contacts to the RNA, it acts as a sensor of RNA secondary structure, suggesting a role for RRM1 in detecting pyrimidine tracts in the context of structured RNA. Moreover, the degree of helix formation depends on the RNA loop sequence. Finally, we show that the alpha 3 helix region, which is highly conserved in vertebrates, is crucial for PTB function in enhancing Encephalomyocarditis virus IRES activity.

1 aMaris, Christophe1 aJayne, Sandrine1 aDamberger, Fred, F.1 aBeusch, Irene1 aDorn, Georg1 aRavindranathan, Sapna1 aAllain, Frederic, H-T uhttps://library.ncl.res.in/content/transient-alpha-helix-n-terminal-rna-recognition-motif-polypyrimidine-tract-binding-protein