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A new colorimetric fluorescent receptor for H(2)PO(4)(-) is reported in this communication. The receptor can detect dihydrogen phosphates optically by developing a color change from yellow to green. Acute spectral responses to H(2)PO(4)(-) in HEPES buffer (DMSO-HEPES 1:9) have been observed. The selectivity zone in terms of pH of the receptor for H(2)PO(4)(-) is attributed to the fitness in the acidity (pK(a)) of receptor with H(2)PO(4)(-). Hydrogen bonding plays the key role here which is confirmed by (1)H NMR titration. The receptor also has good potential for bio-imaging. The mode of interaction has also been established by ab initio calculation.

An endo-β-1,4-xylanase gene xynA of a thermophilic Geobacillus sp. WBI from "hot" compost was isolated by PCR amplification. The gene encoding 407 residues were overexpressed in E. coli and purified by Ni-NTA chromatography. The purified enzyme (47 kDa) had a broad pH optimum of 6.0 to 9.0, and was active between 50 and 90 °C. The enzyme retained 100% of its activity when incubated at 65 °C for 1 h under alkaline condition (pH 10.0) and retained 75% activity at pH 11.0. The K(m) and V(max) of the enzyme were 0.9 mg ml(-1) and 0.8 µmol ml(-1) min(-1), respectively. In molecular dynamics simulation at 338 K (65 °C), the enzyme was found to be stable. At an elevated temperature (450 K) specific α-helix and β-turns of the proteins were most denatured. The denaturation was less in WBI compared with its highest homolog G. stearothermophilus T-6 xylanase with difference of six residues. The results predict that these regions are responsible for the improved thermostability observed over related enzymes. The present work encourages further experimental demonstration to understand how these regions contribute thermostability to WBI xylanase. The study noted that WBI produces a xylanase with unique characteristics, specifically alkali-thermostability.