Kulim Kht Pure Kinetic with MPSPR Bionavis

When is the PureKinetics™ useful?
• with Kinetic measurements of small molecules
• with Interaction measurements on lipid bilayers
• when there are Material interactions with biomolecules
• in case of Solvent interactions
• when using Crude samples (serum, growth medium, lysate, seawater)

IgG dissociation kinetics from immobilized Protein A was
studied using real-time Multi-Parametric Surface Plasmon
Resonance (MP-SPR). Various dissociation buffers were
tested to determine the most efficient solution. A unique
feature, PureKinetics™, allows differentiation of real binding
from interfering bulk signal artifacts, providing a pure
binding signal. The method can clear out even extremely
large bulk signals, such as high-ionic strength dissociation
buffers. In this study, the most efficient dissociation from
Protein A was achieved with buffers of pH below 4.0.

Introduction
Surface Plasmon Resonance (SPR) is a well-established method for
molecule-molecule interaction studies. The SPR is a popular real-time
and label-free method measuring association and dissociation kinetic
constants in addition to the affinity constant. Multi-Parametric Surface
Plasmon Resonance (MP-SPR) is based on the SPR principle, but it utilizes
a unique optical setup which allows to solve challenges related to the
buffer composition changes during SPR measurements.
In non-labelled optical methods, changes in buffer composition
frequently cause a shift of the peak minimum angle value due to a
change in refractive index of the buffer (called bulk effect or solvent
effect). The usual method to counteract this is to subtract a reference
channel response from the measurement channel response. However,
the bulk effect is often not exactly the same in the different measurement
channels because ligands might prevent the liquid flow near the
surface. Sometimes suitable reference surface is hard to find, especially
in the case of interactions to a membrane protein or interactions to
coatings. Therefore, better methods than reference channel correction
to compensate for bulk artifacts are needed.
Many small molecule weight drugs have poor solubility in water-based
liquids, and solubility enhancers such as dimethyl-sulfoxide (DMSO) are
needed to obtain suitable solubility. As the organic solubility enhancers
create a large bulk signal in SPR, they also create huge challenges to
assays in terms of a protein stability and function. Traditionally the bulk
effect caused by DMSO is corrected using an empirical calibration curve
requiring multiple injections [Frostell-Karlsson et al. 2000].
The unique optical setup of the MP-SPR instruments enables
measurement of multiple optical parameters simultaneously and in
real-time. Cross-correlation of the parameters allows simple in line
characterization of the interfering bulk signal using the PureKinetics™
feature.