Biomolecular Interaction Facility

Biolayer interferometry
Biolayer interferometry is a label-free technology for measuring biomolecular interactions. It is an optical analytical technique that analyses the interference pattern of white light reflected from two surfaces: a layer of immobilised protein on the biosensor tip, and an internal reference layer (see Figure 1).  Any change in the number of molecules bound to the biosensor tip causes a shift in the interference pattern that can be measured in real-time. Simple dip and read measurements can be used to perform in-depth kinetic analysis of biomolecular interactions, to determine the amount of biomolecules present in solution, to develop assays and to perform diverse screening applications. A wide range of biosensors are making this system very flexible in application.

Figure 1. Association or dissociation of the target from the sensor (left) results in a change in wavelength (middle), which is translated into a binding curve (right).

Possible applications:

  • Antibody characterisation (e.g. determination of ka, kd and KD for antibody-antigen binding)
  • Protein-protein and protein-peptide interactions
  • Protein-DNA/RNA interactions
  • Protein-lipid/liposome interactions
  • Virus research (e.g. (evolution of) virus-receptor interactions)
  • Protein-small molecule interactions (label-free detection down to 150 Da)

Performance:

Affinity Range

1 mM-10 pM

Molecular weight

>150 Da

Min. sample volume

100-40 µl

Max. simultaneous reads

8-16

Equipment and access
We have two machines (OctetQK and OctetRED384) to perform biolayer-interferometry.

Coordinators

Isothermal Titration Calorimetry
Isothermal Titration Calorimetry (ITC) is a technique used to quantitatively study a wide variety of biomolecular interactions. It works by directly measuring the heat that is either released or absorbed during a biomolecular binding event. ITC is the only technique that can simultaneously determine all binding parameters in a single experiment. Requiring no modification of binding partners, either with fluorescent tags or through immobilisation, ITC measures the affinity of binding partners in their native states. Basically any two soluble molecules that bind each other can be measured. Examples: peptide-DNA; protein-LPS; receptor-ligand, etc.

Measuring heat transfer during binding enables accurate determination of binding constants (KD), reaction stoichiometry (n), enthalpy (∆H) and entropy (ΔS). This provides a complete thermodynamic profile of the molecular interaction (see Figure 2).

Fig. 1: upper panel: heat production upon stepwise titration of one molecule to its binding partner; lower panel: determination of biophysical binding parameters.
Coordinator