02735nas a2200277   4500008004100000022001400041245013100055210006900186260008000255300001400335490000700349520172600356653001702082653002802099653002302127653002102150653001402171653002302185653002002208100002602228700001802254700002202272700002602294700001902320856011802339       2015                        eng d  a1367-543500aSequence and structure-based comparative analysis to assess, identify and improve the thermostability of penicillin G acylases0 aSequence and structurebased comparative analysis to assess ident  aTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANYbSPRINGER HEIDELBERGcNOV  a1493-15060 v423 a<p>Penicillin acylases are enzymes employed by the pharmaceutical industry for the manufacture of semi-synthetic penicillins. There is a continuous demand for thermostable and alkalophilic enzymes in such applications. We have carried out a computational analysis of known penicillin G acylases (PGAs) in terms of their thermostable nature using various protein-stabilizing factors. While the presence of disulfide bridges was considered initially to screen putative thermostable PGAs from the database, various other factors such as high arginine to lysine ratio, less content of thermolabile amino acids, presence of proline in beta-turns, more number of ion-pair and other non-bonded interactions were also considered for comparison. A modified consensus approach designed could further identify stabilizing residue positions by site-specific comparison between mesostable and thermostable PGAs. A most likely thermostable enzyme identified from the analysis was PGA from Paracoccus denitrificans (PdPGA). This was cloned, expressed and tested for its thermostable nature using biochemical and biophysical experiments. The consensus site-specific sequence-based approach predicted PdPGA to be more thermostable than Escherichia coli PGA, but not as thermostable as the PGA from Achromobacter xylosoxidans. Experimental data showed that PdPGA was comparatively less thermostable than Achromobacter xylosoxidans PGA, although thermostability factors favored a much higher stability. Despite being mesostable, PdPGA being active and stable at alkaline pH is an advantage. Finally, several residue positions could be identified in PdPGA, which upon mutation selectively could improve the thermostability of the enzyme.</p>10aAlkalistable10abeta-lactam antibiotics10aConsensus approach10aDisulfide bridge10aIon pairs10aPenicillin acylase10aThermostability1 aPanigrahi, Priyabrata1 aChand, Deepak1 aMukherji, Ruchira1 aRamasamy, Sureshkumar1 aSuresh, C., G.  uhttp://library.ncl.res.in/content/sequence-and-structure-based-comparative-analysis-assess-identify-and-improve-002006nas a2200229   4500008004100000022001400041245014800055210006900203260007500272300001400347490000700361520110400368653002501472653002101497653003101518653001401549653001801563100002201581700002601603700001601629856013101645       2016                        eng d  a1439-423500aComparative investigation of the ionicity of aprotic and protic ionic liquids in molecular solvents by using conductometry and NMR spectroscopy0 aComparative investigation of the ionicity of aprotic and protic   aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcAPR  a1006-10170 v173 a<p>Electrical conductivity (sigma), viscosity (), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4], displays 100% ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (HNMR)-H-1 chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3COO] in D2O and in [D-6]DMSO are determined by using H-1 nuclei with pulsed field gradient spin-echo NMR spectroscopy.</p>10aconducting materials10aElectrochemistry10aelectrostatic interactions10aIon pairs10aionic liquids1 aThawarkar, Sachin1 aKhupse, Nageshwar, D.1 aKumar, Anil  uhttp://library.ncl.res.in/content/comparative-investigation-ionicity-aprotic-and-protic-ionic-liquids-molecular-solvents-using