02966nas a2200229 4500008004100000022001400041245008000055210006900135260009000204300001200294490000800306520214900314653002102463653000802484653002802492653001202520653002102532100002602553700002802579700002802607856010102635 2010 eng d a0022-283600aIncrease in backbone mobility of the VTS1p-SAM domain on binding to SRE-RNA0 aIncrease in backbone mobility of the VTS1pSAM domain on binding  a24-28 OVAL RD, LONDON NW1 7DX, ENGLANDbACADEMIC PRESS LTD- ELSEVIER SCIENCE LTDcFEB a732-7460 v3963 a

The sterile alpha motif (SAM) domain of VTS1p, a posttranscriptional gene regulator, belongs to a family of SAM domains conserved from yeast to humans. Even though SAM domains were originally classified as protein-protein interaction domains, recently, it was shown that the yeast VTS1p-SAM and the SAM domain of its Drosophila homolog Smaug can specifically recognize RNA hairpins termed Smaug recognition element (SRE). Structural studies of the SRE-RNA complex of VTS1p-SAM revealed that the SAM domain primarily recognizes the shape of the RNA fold induced by the Watson-Crick base-pairing in the RNA pentaloop. Only the central G nucleotide is specifically recognized. The VTS1p-SAM domain recognizes SRE-RNAs with a CNGGN pentaloop where N is any nucleotide. The C1-G4 base pair in the wild type can be replaced by any pair of nucleotides that can form base pairs even though the binding affinity is greatest with a pyrimidine in position 1 and a purine in position 4. The interaction thus combines elements of sequence-specific and non-sequence-specific recognitions. The lack of structural rearrangements in either partner following binding is rather intriguing, suggesting that molecular dynamics may play an important role in imparting relaxed specificity with respect to the exact combination of nucleotides in the loop, except for the central nucleotide. In this work, we extend our previous studies of SRE-RNA interaction with VTS1p, by comparing the dynamics of the VTS1p-SAM domain both in its free form and when bound to SRE-RNA. The 1 5 N relaxation studies of backbone dynamics suggest the presence of a dynamic interaction interface, with residues associated with specific G3 recognition becoming more rigid on RNA binding while other regions attain increased flexibility. The results parallel the observations from our studies of dynamics changes in SRE-RNA upon binding to VTS1p-SAM and shows that molecular dynamics could play a crucial role in modulating binding affinity and possibly contribute to the free energy of the interaction through an entropy-driven mechanism. (C) 2009 Elsevier Ltd. All rights reserved.

10a(15)N relaxation10aNMR10aprotein-RNA interaction10aSRE-RNA10aVTS1p-SAM domain1 aRavindranathan, Sapna1 aOberstrass, Florian, C.1 aAllain, Frederic, H. T. uhttps://library.ncl.res.in/content/increase-backbone-mobility-vts1p-sam-domain-binding-sre-rna-001933nas a2200253 4500008004100000022001400041245014900055210006900204260000800273300001200281490000700293520097800300653002501278653003801303653002601341653001301367653002301380653003001403100001701433700003001450700004301480700002601523856013001549 2022 eng d a0959-810300aInvestigation of domain structures in monomethoxy poly(ethylene glycol)-b-poly(caprolactone) grafted poly(acrylic acid) by NMR diffusion studies0 aInvestigation of domain structures in monomethoxy polyethylene g cAUG a976-9840 v713 a

Associating polymers developed by grafting a block copolymer of monomethoxy poly(ethylene glycol)-b-poly(caprolactone) (MPEG-b-PCL) onto poly(acrylic acid) undergo an irreversible sol-gel transition on heating. The influence of various physicochemical parameters on the thermoresponsive behaviour was examined by rheology and NMR studies. Pulsed field gradient NMR diffusion studies were performed to probe the mechanism of thermally induced gelation. Analysis of the diffusion data reveals the presence of loosely and strongly associated structures which respond differently to variation in temperature. It is observed that the polymer solution, which is visibly homogeneous, is heterogeneous on a mesoscopic scale with a distribution of domains. Detailed investigation of the thermally induced sol-gel transition shows that the mechanism of gelation involves irreversible alterations in the domain structure and size. (c) 2022 Society of Industrial Chemistry.

10aassociating polymers10ahydrophobically modified polymers10aNMR diffusion studies10aRheology10asol-gel transition10athermoresponsive polymers1 aTiwari, Neha1 aBadiger, Manohar, Virupax1 aRajamohanan, Pattuparambil, Ramanpilla1 aRavindranathan, Sapna uhttps://library.ncl.res.in/content/investigation-domain-structures-monomethoxy-polyethylene-glycol-b-polycaprolactone-grafted02106nas a2200229 4500008004100000022001400041245008600055210006900141260000900210300001400219490000700233520136100240653001601601653001701617653002701634653001901661653001501680100002701695700002601722700002301748856010501771 2024 eng d a1543-838400aInsights into the structure of sucralfate by advanced solid- and liquid-state NMR0 aInsights into the structure of sucralfate by advanced solid and  cFEB  a1390-14010 v213 a

Sucralfate, which is a sucrose octasulfate aluminum complex, is an active pharmaceutical ingredient (API) falling in the category of cytoprotective agents which are very effective for gastric and duodenal ulcers. On interaction with stomach acid, it ionizes into aluminum and sucrose octasulfate ions to form a protective layer over the ulcerated region inhibiting further attack from acid. The mechanism of action of sucralfate in the context of its structure is not well understood. Considering that at least two forms of this API are available in the market, there are no reports on the various forms of sucralfate and differences in their pharmacological action. We characterized the two forms of sucralfate using multinuclear, multidimensional solid-state NMR, and the results show significant structural differences between them arising from variation in the aluminum environment and the level of hydration. The impact of structural differences on pharmacological action was examined by studying acid-induced Al release by Al-27 liquid-state NMR. The sucralfate, European pharmaceutical standard, Form I, undergoes faster disruption in acid compared to Form II. The difference is explained on the basis of structural differences in the two forms which gives significant insights into the action of sucralfate in relation to its structure.

10a(27)AlMQMAS10aH-1-H-1 DQSQ10apharmacological action10asolid-stateNMR10asucralfate1 aHareendran, Chaithanya1 aRavindranathan, Sapna1 aAjithkumar, T., G. uhttps://library.ncl.res.in/content/insights-structure-sucralfate-advanced-solid-and-liquid-state-nmr02091nas a2200265 4500008004100000022001400041245012200055210006900177260000800246490000800254520116300262653001501425653002101440653003701461653002401498100002701522700001901549700001701568700001901585700002601604700002401630700002501654700002301679856012301702 2026 eng d a0021-899500aInsight Into the Influence of Salinity on Flow and Flocculation Behavior of Acrylamide-Based Cationic Polyelectrolyte0 aInsight Into the Influence of Salinity on Flow and Flocculation  cMAR0 v1433 a

The viscometric behavior of aqueous solutions of acrylamide and acrylamidopropyl trimethylammonium chloride copolymers (AM-co-APTMAC) with varying cationic content under different salinity conditions was studied. Viscometric measurements were employed to determine intrinsic viscosity and quantify the influence of electrostatic interactions on chain conformation. Rheology experiments were performed to probe dynamic flow behavior under shear to obtain insights into polyelectrolyte viscoelastic properties under conditions mimicking industrial processes. Viscometric and rheology data analysis is augmented with insights from NMR relaxation and pulsed field gradient NMR diffusion experiments. Further, flocculation of kaolin suspensions was studied using aqueous solutions of AM-co-APTMAC copolymers with different charge fractions in the presence and absence of salt. The physicochemical insights on the behavior of AM-co-APTMAC polyelectrolytes in solution from this study could be relevant in practical applications, such as plants that use seawater or in cases where the ionic strength of suspensions is high due to salinity in the medium.

10acopolymers10apolyelectrolytes10astructure property relationships10atheory and modeling1 aRanganath, Suresha, P.1 aKurian, Rachna1 aTorris, Arun1 aKhairnar, Ajay1 aRavindranathan, Sapna1 aRajamohanan, P., R.1 aBadiger, Manohar, V.1 aWolf, Bernhard, A. uhttps://library.ncl.res.in/content/insight-influence-salinity-flow-and-flocculation-behavior-acrylamide-based-cationic