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Study the effect on membrane structure of helical antimicrobial peptides (HPA3 and HPA3P) by Dual polarization interferometry (DPI) (CAT#: STEM-MB-0426-WXH)

Introduction

Hp, a cecropin-like antimicrobial peptide derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1), possesses a broad-spectrum activity against bacteria, fungi and protozoa at low micromole concentration without causing haemolysis. In addition to their pro-inflammatory role as a monocyte chemoattractant, various analogues of Hp(2–20) have been designed and synthesised in an attempt to enhance its antimicrobial activity. HPA3 and HPA3P are analogues of Hp(2–20).
Monitoring the effect of these peptides on a structurally characterised bilayer has provided further insight into the role of membrane structure changes in the molecular basis of peptide selectivity and activity and may assist in defining the mode of antimicrobial action.




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

Quantitatively analyse the interaction of two helical antimicrobial peptides (HPA3 and HPA3P).
Development of new and more effective antimicrobial agents.
Drug Discovery.

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
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