01869nas a2200145   4500008004100000245011000041210006900151260000800220300001200228490000800240520129800248100002501546700002501571856012701596       2017                        eng d00aKinetics and thermodynamics of transpeptidation catalysed by Bacillus subtilis gamma glutamyl transferase0 aKinetics and thermodynamics of transpeptidation catalysed by Bac  cJUN  a109-1130 v54 3 aGamma glutamyl transferases (GGT) catalyse the removal (deglutamylation) of the terminal gamma-glutamate residue from compounds such as glutathione and poly-gamma-glutamic acid and its transfer either to a water molecule (hydrolysis) or to a peptide/amino acid (transpeptidation). We analysed the kinetics of Bacillus subtilis GGT (BsGGT) catalysed transpeptidation using gamma-glutamyl-(3-carboxyl)-4-nitroaniline as the gamma-glutamate-donor and glycylglycine (Gly-Gly) as the gamma-glutamate acceptor. Addition of Gly-Gly improved the affinity (Km) of the enzyme for gamma-glutamyl-(3-carboxyl)-4-nitroaniline by nearly 25 times with negligible impact on the rate of deglutamylation (V-max). The asymmetric changes in the kinetic parameters improved the specificity constant (K-cat/K-m.) by about 43 times. BsGGT catalysed transpeptidation was pronounced in conditions that are unfavorable for hydrolysis. Maximum transpeptidation occurred near neutral pH and when the concentration of the gamma-glutamate-donor substrate is lower. The effect of Gly-Gly on the kinetics of BsGGT is contrastingly different from that observed for eukaryotic GGTs. In the case of mammalian GGTs, the addition of Gly-Gly increases both Km and k(cat); and, the specificity constant (K-cat/K-m) remains unaltered1 aBalakrishna, Sharath1 aPrabhune, Asmita, A.  uhttps://library.ncl.res.in/content/kinetics-and-thermodynamics-transpeptidation-catalysed-bacillus-subtilis-gamma-glutamyl01598nas a2200205   4500008004100000022001400041245011200055210006900167260000800236300001100244490000600255520088300261653001301144653001801157653002101175653001701196100002201213700002501235856013201260       2018                        eng d  a2054-570300aPhotophysical studies on curcumin-sophorolipid nanostructures: applications in quorum quenching and imaging0 aPhotophysical studies on curcuminsophorolipid nanostructures app  cFEB  a1708650 v53 a<p>Sophorolipid biosurfactants are biodegradable, less toxic and FDA approved. The purified acidic form of sophorolipid is stimuli-responsive with self-assembling properties and used for solubilizing hydrophobic drugs. This study encapsulated curcumin (CU) with acidic sophorolipid (ASL) micelles and analysed using photophysical studies like UV-visible spectroscopy, photoluminescence (PL) spectroscopy and timecorrelated single photon counting (TCSPC). TEM images have revealed ellipsoid micelles of approximately 100nm size and were confirmed by dynamic light scattering. The bacterial fluorescence uptake studies showed the uptake of formed CUASL nanostructures into both Gram-positive and Gram-negative bacteria. They also showed quorum quenching activity against Pseudomonas aeruginosa. The results have demonstrated this system has potential theranostic applications.</p>10acurcumin10aphotophysical10aQuorum quenching10aSophorolipid1 aVasudevan, Sahana1 aPrabhune, Asmita, A.  uhttps://library.ncl.res.in/content/photophysical-studies-curcumin-sophorolipid-nanostructures-applications-quorum-quenching-and01752nas a2200193   4500008004100000022001400041245007200055210006900127260000800196300001600204490000600220520113300226100002201359700001501381700002101396700002501417700001701442856009901459       2020                        eng d  a2470-134300aLauric acid sophorolipid: accelerating the gelation of silk fibroin0 aLauric acid sophorolipid accelerating the gelation of silk fibro  cNOV  a28571-285780 v53 a<p>Silk fibroin (SF) hydrogels find wide applications in tissue engineering. However, their scope has been limited due to the long gelation time in ambient conditions. This paper shows the reduction in gelation time of silk fibroin to minutes upon doping with a newly synthesized lauric acid sophorolipid (LASL). LASL comprises a fatty acid, lauric acid (with a 12-carbon aliphatic chain), that is derivatized by glucose molecules using a non-pathogenic yeast Candida bombicola. LASL was characterized using spectroscopic (Fourier transform infrared spectroscopy) and chromatographic (high-performance liquid chromatography, thin-layer chromatography, and high-resolution mass spectrometry) methods. This gelation of SF is comparable to the effect of an anionic surfactant, sodium dodecyl sulfate (SDS). The microstructure of SF-LASL hydrogels was investigated by small-angle neutron scattering (SANS) measurements and exhibited the beads-on-a-necklace model. The rheological properties of these hydrogels show similarity to SF-SDS hydrogels, therefore presenting a greener alternative for tissue engineering applications.</p>
1 aHirlekar, Swarali1 aRay, Debes1 aAswal, Vinod, K.1 aPrabhune, Asmita, A.1 aNisal, Anuya  uhttps://library.ncl.res.in/content/lauric-acid-sophorolipid-accelerating-gelation-silk-fibroin02277nas a2200193   4500008004100000022001400041245009600055210006900151260000800220300001400228490000600242520159700248100002001845700001701865700002501882700001701907700002901924856013001953       2021                        eng d  a2470-134300aMyristic acid derived sophorolipid: efficient synthesis and enhanced antibacterial activity0 aMyristic acid derived sophorolipid efficient synthesis and enhan  cJAN  a1273-12790 v63 a<p>Microbial glycolipids are one of the most interesting alternatives to chemical-based surfactants as they exhibit improved biodegradability and less toxicity. However, their potential has been limited because of specificity of the yeast toward fatty acids having a carbon 16 or carbon 18 chain. This study focuses on sophorolipid (SL) production by the yeast Starmerella bombicola using myristic acid, a medium-chain carbon-14 fatty acid that has not been used as a substrate for SL production. The production was optimized for inoculum size and lipophilic substrate concentration. Furthermore, we also studied the effect of medium-chain fatty acid on yeast cell growth and optimized the process for excellent yield. The myristic acid SL (MASL) so synthesized consisted of mono- and diacetylated forms with preferential glycosylation at the methyl end group, as determined by high-resolution mass spectrometry. Individual congeners of the crude mixture were separated using dry column chromatography and then structurally characterized by mass spectrometry. The synthesized MASL was also shown to have promising surface tension, lowering abilities with a low CMC of 14 mg/L. The SL derived from myristic acid exhibited superior antibacterial activity as compared to SL derived from oleic acid. MASL was also found to be more potent against Gram-positive organisms as compared to Gram-negative organisms. This work, therefore, demonstrates successful synthesis of myristic acid-derived SL and its superior antibacterial activity, establishing a promising future for this biosurfactant.</p>
1 aAbhyankar, Isha1 aSevi, Ganesh1 aPrabhune, Asmita, A.1 aNisal, Anuya1 aBayatigeri, Santhakumari  uhttps://library.ncl.res.in/content/myristic-acid-derived-sophorolipid-efficient-synthesis-and-enhanced-antibacterial-activity01919nas a2200229   4500008004100000022001400041245016200055210006900217260000800286520105900294653002801353653002501381653002201406653001901428653001401447653001601461100002501477700002101502700002501523700001801548856012301566       2021                        eng d  a0302-893300aRed fluorescent ultra-small gold nanoclusters functionalized with signal molecules to probe specificity in quorum sensing receptors in gram-negative bacteria0 aRed fluorescent ultrasmall gold nanoclusters functionalized with  cJUN3 aUltra-small (size < 2 nm) gold nanoclusters (AuNCs) are used as fluorescent probes which have excellent applications in bioimaging and sensing due to their emission in visible and NIR spectral region. Here, this property is exploited for understanding the quorum sensing phenomenon in bacteria which is regulated by signal molecules which are specific to various species. AuNCs are then functionalized with the signal molecules, Acyl Homoserine Lactones (AHL) of varying carbon chain length, C-6, C-8, and C-12 without 3rd C modification, to sense different strains of gram-negative bacteria i.e., Escherichia coli, Cronobacter sakazakii and Pseudomonas aeruginosa. In the concentration employed, selectivity to a limited extent is observed between the three Gram-negative bacteria tested. E. coli showed emission with all the AHL conjugates and P. aeruginosa did not interact with any of the three conjugates, whereas C. sakazakii showed specificity to C-8AHL. This is probably due to selectivity for cognate AHL molecules of appropriate concentrations.10aacyl homoserine lactone10afluorescence imaging10aGold nanoclusters10aquorum sensing10aReceptors10aselectivity1 aChahande, Anurag, M.1 aLathigara, Disha1 aPrabhune, Asmita, A.1 aDevi, Nandini  uhttps://library.ncl.res.in/content/red-fluorescent-ultra-small-gold-nanoclusters-functionalized-signal-molecules-probe