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Detection of lysozyme crystallization processes by Dual polarization interferometry (DPI) (CAT#: STEM-MB-0389-WXH)

Introduction

Lysozyme is an enzyme that is able to lyse bacterial cell membranes and thus serve as an antimicrobial agent in foods. Lysozyme occurs naturally in egg white, but the purified enzyme is used on occasion as an additive in other foods, especially soft cheeses. Lysozyme is a well-documented egg white allergen. Lysozyme can be utilized as model protein in crystallization experiments and X-ray structure analysis.<br />Protein crystallization is the process of formation of a regular array of individual protein molecules stabilized by crystal contacts. Once formed, these crystals can be used in structural biology to study the molecular structure of the protein, particularly for various industrial or medical purposes.




Principle

Dual polarization interferometry (DPI) is an analytical technique that allows the simultaneous determination of thickness, density, and mass of a biological layer on a sensing waveguide surface in real time. DPI focuses laser light into two waveguides. One of these functions as the "sensing" waveguide having an exposed surface while the second one functions to maintain a reference beam. A two-dimensional interference pattern is formed in the far field by combining the light passing through the two waveguides. The DPI technique rotates the polarization of the laser, to alternately excite two polarization modes of the waveguides. Measurement of the interferogram for both polarizations allows both the refractive index and the thickness of the adsorbed layer to be calculated. These measurements can be used to infer conformational information about the molecular interactions taking place, as the molecule size (from the layer thickness) and the fold density (from the RI) change.

Applications

Detection of lysozyme crystallization processes.
Drug discovery.
Study the molecular structure of the lysozyme.

Procedure

1. Setting of dual polarization interferometry
2. Preparing the DPI sensor chip
3. Immobilization of target on DPI biosensor
4. Reagent was injected to react
5. Quantitative analysis

Materials

• DPI biosensor
• DPI sensor chip