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1.
A novel polycationic ionen was synthesized and fractionated on carboxymethyl-Sephadex using a salt gradient in 7M urea. A
series of oligomers of discrete length were characterised by ultraviolet spectra. The ultraviolet spectra of oligomers revealed
a new band centred at 232.5 nm which was probably due to exciton splitting. Thermal denaturation studies indicated both stabilization
of the helix conformation and a higher degree of cooperativity in the melting of DNA (oligomers)n complex as compared to native
calf thymus DNA. Ionen oligomers exhibited large extrinsic Cotton effect at 232.5 nm which could be attributed to exciton
interaction. 相似文献
2.
M. G. Kotresh K. S. Adarsh M. A. Shivkumar B. G. Mulimani M. I. Savadatti S. R. Inamdar 《Luminescence》2016,31(3):760-768
Quantum dots (QDs), bright luminescent semiconductor nanoparticles, have found numerous applications ranging from optoelectronics to bioimaging. Here, we present a systematic investigation of fluorescence resonance energy transfer (FRET) from hydrophilic ternary alloyed quantum dots (CdSeS/ZnS) to cresyl violet dye with a view to explore the effect of composition of QD donors on FRET efficiency. Fluorescence emission of QD is controlled by varying the composition of QD without altering the particle size. The results show that quantum yield of the QDs increases with increase in the emission wavelength. The FRET parameters such as spectral overlap J(λ), Förster distance R0, intermolecular distance (r) , rate of energy transfer kT (r), and transfer efficiency (E) are determined by employing both steady‐state and time‐resolved fluorescence spectroscopy. Additionally, dynamic quenching is noticed to occur in the present FRET system. Stern–Volmer (KD) and bimolecular quenching constants (kq) are determined from the Stern–Volmer plot. It is observed that the transfer efficiency follows a linear dependence on the spectral overlap and the quantum yield of the donor as predicted by the Förster theory upon changing the composition of the QD. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
alpha-Galactosidase and invertase were accumulated in a coherent middle phase in a three-phase partitioning system under different conditions (ammonium sulphate, ratio of tert-butanol to crude extract, temperature and pH). alpha-Galactosidase and invertase were purified 15- and 12-fold with 50 and 54% activity recovery, respectively. The fractions of interfacial precipitate arising from the three-phase partitioning were analyzed by SDS-PAGE. Both purified preparations showed electrophoretic homogeneity on SDS-PAGE. 相似文献
4.
5.
Chitosan beads were modified with glutaraldehyde and modified chitosan was investigated as matrix for hydrophobic interaction chromatography. The influence of temperature, type of salt and its ionic strength on the adsorption of -galactosidase was studied. -Galactosidase was found to bind in presence of high concentration of ammonium sulphate (3 M, w/v) and 90% of the bound enzyme was eluted with decreasing salt concentration in presence of 10% ethylene glycol. Attempt was made to purify -galactosidase from modified chitosan, -galactosidase showed 1.7-fold purification with 43.96% recovery of enzyme activity. The SDS–PAGE analysis of enzyme showed considerable purification and its molecular weight was found to be 63–64 kDa. Unlike other chromatographic matrices, the prepared chitosan beads were used five times. The results showed that purification and recovery of the enzyme did not change even when column size was increased. 相似文献
6.
Simple, attractive and versatile technique, three-phase partitioning (TPP) was used to purify α-galactosidase from fermented
media of Aspergillus oryzae. The various conditions required for attaining efficient purification of the α-galactosidase fractions were optimized. The
addition of n-butanol, t-butanol, and isopropanol in the presence of ammonium sulfate pushes the protein out of the solution to form an interfacial
precipitate layer between the lower aqueous and upper organic layers. The single step of three-phase partitioning, by saturating
final concentration of ammonium sulfate (60%) with 1:1 t-butanol, gave activity recovery of 92% with 12-fold purification at second phase of TPP. The final purified enzyme after
TPP showed considerable purification on SDS-PAGE with a molecular weight of 64 kDa. The enzyme after TPP showed improved activity
in organic solvents. Results are compared with conventional established processes for the purification of α-galactosidase
produced by Aspergillus oryzae and overall the proposed TPP technique resulted in 70% reduction of purification cost compared to conventional chromatographic
protocols. 相似文献
7.
K. S. Adarsh M. K. Singh M. G. Kotresh Laxmi S. Inamdar M. A. Shivkumar B. N. Jagatap B. G. Mulimani S. R. Inamdar 《Luminescence》2017,32(1):35-42
We present here a systematic investigation on the interaction between a water‐soluble alloyed semiconductor quantum dot and bovine serum albumin using various spectroscopic techniques i.e. fluorescence quenching, resonance light scattering and synchronous fluorescence spectroscopy. The analysis of fluorescence spectrum and fluorescence intensity indicates that the intrinsic fluorescence of bovine serum albumin (BSA) gets quenched by both static and dynamic quenching mechanism. The Stern‐Volmer quenching constants, energy transfer efficiency parameters, binding parameters and corresponding thermodynamic parameters (ΔH0, ΔS0 and ΔG0) have been evaluated by using van 't Hoff equation at different temperatures. A positive entropy change with a positive enthalpy change was observed suggesting that the binding process was an entropy‐driven, endothermic process associated with the hydrophobic effect. The intermolecular distance (r) between donor (BSA) and acceptor (CdSeS/ZnS quantum dots) was estimated according to Förster's theory of non‐radiative energy transfer. The synchronous fluorescence spectra revealed a blue shift in the emission maxima of tryptophan which is indicative of increasing hydrophobicity. Negative ΔG0 values implied that the binding process was spontaneous. It was found that hydrophobic forces played a role in the quenching process. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
The use of crude -galactosidase from Gibberella fujikuroi to reduce the flatulence-inducing raffinose family sugars in chickpea flour was studied. Crude enzyme treatment of chickpea flour resulted in complete hydrolysis of sugars of the raffinose family. This method could be useful on commercial scale. 相似文献
9.
Shankar SK Kumar SK Mulimani VH 《Journal of industrial microbiology & biotechnology》2011,38(9):1399-1405
Thermostable α-galactosidase from Aspergillus terreus
GR was insolubilized using concanavalin A obtained from jack bean extract and in order to maintain the integrity of complex
in the presence of its substrate or products, this complex was crosslinked with glutaraldehyde. Soluble α-galactosidase entrapped
in calcium alginate retained 82% of enzyme activity whereas, Con A-α-galactosidase complex entrapped in calcium alginate and
crosslinked Con A-α-galactosidase complex entrapped calcium alginate retained 74 and 61% activity, respectively. A fluidized
bed reactor was constructed for continuous hydrolysis of galactooligosaccharides in soymilk using crosslinked Con A-α-galactosidase
complex entrapped calcium alginate. Optimum conditions such as pH (5.0) and temperature (65°C) were the same for all immobilized
enzyme preparations and soluble enzyme. Crosslinked Con A-α-galactosidase entrapped complex exhibited enhanced thermostability
and showed 62% of activity (38%) after 360 min at 65°C. Entrapped crosslinked Con A-α-galactosidase complex preparation was
superior in the continuous hydrolysis of oligosaccharides in soymilk by batch processes compared to the other entrapped preparations.
The entrapped crosslinked concanavalin A-α-galactosidase complex retained 95% activity after eight cycles of use. 相似文献
10.
Comparisons were made for alpha-galactosidase production using red gram plant waste (RGPW) with wheat bran (WB) and other locally available substrates using the fungus Aspergillus oryzae under solid-state fermentation (SSF). RGPW proved to be potential substrate for alpha-galactosidase production as it gave higher enzyme titers (3.4 U/g) compared to WB (2.7 U/g) and other substrates tested. Mixing WB with RGPW (1:1, w/w) resulted enhanced alpha-galactosidase yield. The volume of moistening agent in the ratio of 1:2 (w/v), pH 5.5 and 1 ml (1 x 10(6) spores) of inoculum volume and four days incubation were optimum for alpha-galactosidase production. Increase in substrate concentration (RGPW+WB) did not decrease enzyme yield in trays. 相似文献