Mg/Al Layered Double Hydroxides (LDHs) were functionalized to immobilize the serine protease, trypsin. Three methods were implemented for immobilization: physical adsorption, entrapment and covalent cross-linking. Trypsin was immobilized in Mg/Al-NO 3-LDH via simple adsorption. The same LDH host was modified with Sodium Dodecyl Sulphate (SDS) which assembles inside the double layer, for the enzyme to be entrapped. For covalent cross linking, LDH host was modified with vertical pillars of glutamate ions which were cross-linked to horizontally aligned dicarbonyl linkers. This cross linkage firmly holds the enzyme via Schiff's base linkages using the free amino groups of the enzyme. Thermal stability and storage stability of the immobilized enzyme was studied in comparison with the free enzyme using trypsin activity assay experiments. The enzyme showed remarkable stability against autolysis even at higher temperatures showing the potential of modified LDHs to store trypsin at room temperature.
Chitinases belong to a diverse family of enzymes among many other hydrolytic enzymes of the pitcher fluid of Nepenthes sp. There are no existing studies on identification of chitinases in Nepenthes distillatoria the only representative of the genus Nepenthes in Sri Lanka. In this study an assay procedure was developed and optimized to detect the chitinolytic activity in the pitcher fluid of N. distillatoria using colloidal Chitin Azure as the substrate. Crude Nepenthes pitcher fluid was subjected to DEAE Cellulose chromatography in an attempt to partially purify and separate chitinases. The optimum pH, temperature and incubation time for the chitinolytic activity were 5.0, 27 °C and 30 min, respectively. DEAE Cellulose Chromatography revealed the presence of more than one type of chitinases within the pitcher juice. Further studies are required to characterize and confirm the origin/s of these chitinases.
Pollution of water is a pragmatic problem in the world today. Contamination by heavy metals and dyes is a major concern of water pollution. This study examines a new adsorbent made by the reaction between para-nitroacetanilide and concentrated sulfuric acid and is the first-ever study carried out to the best of our knowledge. The adsorption of Cu 2+ has been studied on this adsorbent as a preliminary study. The prepared material was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Fluorescence Spectroscopy (XRF), Powder X-ray Diffraction (PXRD) and point of zero charges (pzc) analysis. The average pore diameter obtained from SEM analysis was 2 μm, concluding that the adsorbent has a desirable morphology for better adsorption. The adsorption experiments were carried out as a function of pH, shaking time, initial Cu 2+ concentration, and adsorbent dosage. The adsorption kinetics at low concentrations (34.50 mg L -1 = 1.5 10 -7 mol m -3 ) follows pseudo-second-order kinetics with an R 2 value of 0.99, suggesting a chemisorption process. The adsorption data agree with the Freundlich isotherm at higher concentrations (varying from 17.21 mg L -1 (7 10 -8 mol m -3 ) to 96.25 mg L -1 (3.6 10 -7 mol m -3 ) revealing multilayer adsorption, amounting to a maximum adsorption capacity of 8.31 mg g -1 at 25 ̊ C.
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