Purification and characterization of a thermoalkaline, cellulase free thermostable xylanase from a newly isolated Anoxybacillus sp. Ip-C from hot spring of Ladakh

An alkaline, highly thermostable cellulase free xylanase was purified from a thermophilic Anoxybacillus sp. Ip-C, newly isolated from hot spring of Ladakh. The enzyme was purified using ammonia sulphate precipitation followed by Sephadex G-75. The molecular weight of the xylanase was about 45 kDa, as analyzed by SDS-PAGE. The enzyme had optimum activity at pH 9.0 and 70ºC temperature; the enzyme retained 90% of its original activity for 96 hrs at 70 ºC. Vmax and Km of the enzyme were found to be 13.5 µmol min-1 mg-1 protein and 4.59 mg ml-1, respectively. Metal ions, Ca+2, Fe+2 and Mg+2 highly enhance the enzyme activity to 122.45, 119.06 and 118.98% respectively; whereas SDS and Hg+2 completely inhibit (0 U/ml) the enzyme activity. TLC analysis of enzymatic hydrolysis products showed that this xylanase is an endoxylanase, and generates xylooligosaccharides. Thus, it provides a potential thermostable alkaline xylanase for industrial applications

A rhodamine derivative as a "lock" and SCN- as a "key": Visible light excitable SCN- sensing in living cells

A visible light excitable rhodamine based probe operates as a SCN - selective fluorescent "turn-on" sensor for living cell imaging with a detection limit of 0.01 μM, which is much lower than the normal SCN- level in the human body. A "lock" and "key" model has been proposed to explain the fluorescence enhancement of the rhodamine probe in the presence of SCN-. © 2013 The Royal Society of Chemistry

Nickel(II)-Induced Excimer Formation of a Naphthalene-Based Fluorescent Probe for Living Cell Imaging

Ni²⁺-induced intramolecular excimer formation of a naphthalene-based novel fluorescent probe, 1-[(naphthalen-3-yl)­methylthio]-2-[(naphthalen-6-yl)­methylthio]­ethane (<b>L</b>), has been investigated for the first time and nicely demonstrated by excitation spectra, a fluorescence lifetime experiment, and ¹H NMR titration. The addition of Ni²⁺ to a solution of <b>L</b> (DMSO:water = 1:1, v/v; λ_em = 345 nm, λ_ex = 280 nm) quenched its monomer emission, with subsequent enhancement of the excimer intensity (at 430 nm) with an isoemissive point at 381 nm. The fluorescence lifetime of free <b>L</b> (0.3912 ns) is much lower than that of the nickel­(2+) complex (1.1329 ns). <b>L</b> could detect Ni²⁺ as low as 1 × 10^–6 M with a fairly strong binding constant, 2.0 × 10⁴ M^–1. Ni²⁺-contaminated living cells of plant origin could be imaged using a fluorescence microscope

Nickel(II)-Induced Excimer Formation of a Naphthalene-Based Fluorescent Probe for Living Cell Imaging

Ni²⁺-induced intramolecular excimer formation of a naphthalene-based novel fluorescent probe, 1-[(naphthalen-3-yl)­methylthio]-2-[(naphthalen-6-yl)­methylthio]­ethane (<b>L</b>), has been investigated for the first time and nicely demonstrated by excitation spectra, a fluorescence lifetime experiment, and ¹H NMR titration. The addition of Ni²⁺ to a solution of <b>L</b> (DMSO:water = 1:1, v/v; λ_em = 345 nm, λ_ex = 280 nm) quenched its monomer emission, with subsequent enhancement of the excimer intensity (at 430 nm) with an isoemissive point at 381 nm. The fluorescence lifetime of free <b>L</b> (0.3912 ns) is much lower than that of the nickel­(2+) complex (1.1329 ns). <b>L</b> could detect Ni²⁺ as low as 1 × 10^–6 M with a fairly strong binding constant, 2.0 × 10⁴ M^–1. Ni²⁺-contaminated living cells of plant origin could be imaged using a fluorescence microscope