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Buffers for small molecule screening

Buffers

All buffers used in Biacore, both as running buffer and for sample and reagent preparation, should be filtered through a 0.22 µm filter and degassed. Use Teflon or nylon filters for buffers containing DMSO: do not use cellulose acetate filters.

Phosphate-buffered saline (PBS) is recommended as a buffer for most routine assays. Many different “standard” recipes are available for PBS, and any of these should be acceptable. Use ionic strength at or close to physiological levels (150 mM monovalent ions) to reduce non-specific binding of compounds to the sensor surface. For work with kinases as target molecules, Tris-based buffers are recommended instead of PBS.

When DMSO is included in the buffer, the pH of stock buffer solutions will need to be adjusted to compensate for the effect of DMSO on the pH in the final working buffer (addition of DMSO raises the pH slightly).

Buffer compatibility

It is important that all solutions used (running buffer, sample solutions, regeneration and wash solutions) are compatible with each other and do not precipitate on mixing.

When using PBS as a running buffer, bear in mind that phosphate buffers can form precipitates with additives such as calcium, or on contact with some regeneration solutions such as high concentrations of MgCl₂. If MgCl₂ is used for regeneration, do not exceed 3M MgCl₂ for regeneration and 10 mM phosphate for running buffer. Higher concentrations of either will cause precipitation at the injection interface between regeneration solution and running buffer.

See also

List of help files

Assay design for small molecule screening