Title
Sustained and improved enzymatic activity of trypsin immobilized in the Langmuir Blodgett film of DPPC: A rapid enzyme sensor for the detection of Azocasein
Author
Saumen Saha, Joydeep Chowdhury
Year
2020
Journal
Materials Chemistry and Physics
Abstract
Immobilizing enzymes on biomimicking monolayer ultrathin films of phospholipids exhibit enhanced enzymatic activities (EAs) useful for biosensing applications. Preparation of such substrates with enzyme Trypsin (TRYP) immobilized in dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) matrix with enhanced and sustained enzymatic activity is a real challenge, as the isoelectric point of TRYP is reported to exist at pH ~ 10.5. This paper reports for the first time a facile procedure to fabricate smart substrates of TRYP entrapped in the DPPC monolayer using Langmuir–Blodgett (LB) technique. The incorporation of TRYP into DPPC monolayer at the air–water interface has been demonstrated from adsorption kinetics (π – t), room temperature surface pressure–area (π – A) isotherm plot and compressibility (β – π) studies. Circular dichroism (CD) and Grazing angle IR (GAIR) spectra signify changes in the secondary structure of incubated TRYP when immobilized in DPPC monolayer. Improved and sustained EA of TRYP upon its incubation on the organized monolayer LB films of DPPC has been observed. The reason behind such improvement in the EA of immobilized TRYP has also been suggested. The as fabricated substrates of immobilized TRYP can be used to sense soy milk, soy yoghurt, mayonnaise, meringue etc. using Azocasein as the protease substrate.
Instrument
J-815, V-630, FP-8300
Keywords
Circular dichroism, Secondary structure, Protein folding, Solid state, Fluorescence, Protein structure, Absorption, Quantitation, Kinetics, Biochemistry, Materials