Molecular Interactions

The core measures association rates, dissociation rates, and dissociation constants for pairs of molecules by BioLayer Interferometry using a fortéBIO Octet.  

fortéBIO OctetIn the fortéBIO instrument, a protein is bound to the end of a glass probe which is dipped into
a solution of analyte. Light reflected from the end of the probe and from the interface of the solution and  immobilized protein layer make interference patterns which are altered by the amount of material on the probe. See http://www.fortebio.com/interactions/Spring_2012/page5.html.

Measuring the the amount of analyte bound as a function of time gives an association rate; after removing the analyte solution, the dissociation rate is measured. The two rates are used to calculate a dissociation constant.

Techniques for coupling proteins to the glass are similar to those used by Biacore and other SPR instruments. fortéBIO suggests biotinylation of protein which then binds to a streptavidin derivatized probe.

The most common probes are relatively cheap and thus may be discarded after one reading, rather than attempting regeneration for further uses as done with chips used in SPR machines. The analyte solution is placed in a 96 well plate so that samples do not enter fluidics and in the event of problems, everything which contacts the sample can be discarded without contaminating the instrument. Very little sample is consumed so that most can be recovered from the 96 well plate.

The Octet instrument can read 8 samples simultaneously reducing time for measurements.

It can also perform ELISA type measurements with a reported sensitivity down to pg/ml and a dynamic range of 2000; conversion from ELISA to Octet can be straightforward. The Octet can give data within 30 min of starting with higher precision.

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