Fluorescent Studies of Lysozyme Immobilised Chitosan/Polystyrene Sulphonate Multilayer Membranes

Abstract

The fluorescence emission properties of lysozyme immobilized at selected pH 5, 8.8 and 10.6 on chitosan/polystyrene sulfonate (CHI/PSS) multilayer membranes were investigated. The tryptophanyl fluorescence was selectively excited at 290 nm. The emission maximum and fluorescence intensity were found to be dependent on the pH of lysozyme solution. The fluorescence intensity was highest at pH 8.8. A slight red shift was observed as the pH changes from 5 to 10.6. Quenching of lysozyme fluorescence by iodide was used to study the effect of pH on the adsorption pattern of lysozyme to multilayers. For lysozyme (pH 10.6) adsorbed membrane, the fluorescence intensity was found to decrease progressively with quencher concentration. Almost complete quenching of fluorescence was observed when the iodide concentration was 1 M suggesting full accessibility of quencher to tryptophanyl residues. A linear Perrin plot was obtained suggesting a static mechanism for quenching under the experimental conditions. Fluorescence quenching studies were also carried out with lysozyme (pH 5) adsorbed membranes prepared by normal adsorption methods and also under ultrafiltration conditions. The quenching efficiency was different for the two sets of membranes. The fluorescence quenching studies reveals that adsorption pattern of proteins on multilayers strongly depend on pH and immobilization method.

An eminent approach towards next generation solvents for sustainable packaging and stability of enzymes: a comprehensive study of ionic liquid and deep eutectic solvent mixtures

“…However, Lyz contains six Trp residues in various domains, two of which are Trp 62 and Trp 108, which are partially exposed to the co-solvents and behave as an intrinsic fluorescence probe. 38 Thus, changes in intrinsic fluorescence were employed to understand the conformational changes caused by incorporating the protein into the studied ILs, DES and HIFs in contrast to a buffer. Herein, Lyz in the buffer was excited at 290 nm, and the emission maximum ( λ max ) was observed at 340 nm.…”