Sunitinib-Red

Sunitinib-Red is a derivative of Sunitinib, and has been validated as a fluorescent tracer for HTRF Kinase Binding assays.

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  • No-wash
  • Non-radioactive

Sunitinib-Red is a derivative of Sunitinib, and has been validated as a fluorescent tracer for HTRF Kinase Binding assays.

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Overview

This compound is derived from Sunitinib, which is a well known inhibitor of the PDGF and VEGF RTK families. Sunitinib, which is an ATP-competitive Kinase inhibitor, is used as a drug to treat renal cell carcinoma and imatinib-resistant gastrointestinal stromal tumors. It has been shown to bind with an affinity of <100 nM to about 18% of the Kinases (both RTK and Ser/Thr). It is therefore useful to address multiple Kinases  in the HTRF Kinase Binding assay platform.. The ‘d2’ fluorescent dye used absorbs with its maximum near 650 nm and fluoresces near 670 nm. It is used as an acceptor molecule in HTRF assays.

Sunitinib-Red is supplied as a 25 µM solution in DMSO.

Kd determination assay principal

​The binding of Sunitinib-Red is detected in a sandwich assay format using the Anti Tag labeled with Europium Cryptate (donor), which binds to the tagged Kinase, and a red fluorescent tracer labelled with d2 (acceptor).

The detection principle is based on HTRF® technology. The HTRF ratio (665/620) will increase upon the addition of more of the tracer, and will saturate depending on the dissociation constant (Kd) of the tracer to the tagged kinase.

 ​​​To know whether Sunitinib-Red is the tracer best suited to your tagged kinase of interest, we advise you to try the Kinase Binding Discovery kits.

Kd determination assay protocol

Saturation binding experiments of  Sunitinib-Red can be run in 96- or 384-well plates (20 µL final volume).

First, a dilution series ranging between 0 and 1  µM of Sunitinib-Red in the Kinase Binding Buffer  is prepared in a 96-well non-binding plate. Next, 5 µL of Kinase Binding Buffer are dispensed into the final 96- or 384-well plate. Then 5 µL of tagged-Kinase are added, followed by 5 µL of Anti-tag Eu-cryptate. Finally, 5 µL of the red tracer solution are added. 

The HTRF ratio is measured after 1H of incubation.

IC50/Ki determination assay principle

The binding of Sunitinib-Red is detected in a sandwich assay format using a specific Anti-GST, 6HIS antibody or Streptavidin labeled with Europium Cryptate (donor), which binds to the tagged Kinase, and a red fluorescent Sunitinib labelled with d2 (acceptor).

The detection principle is based on HTRF® technology.  The HTRF ratio (665/620) will increase upon the addition of more Sunitinib-Red, and will saturate depending on the dissociation constant (Kd ) of Sunitinib-Red to the tagged kinase.

When an inhibitor of the kinase is added, Sunitinib-Red will be displaced and the HTRF signal will disappear, depending on the dose.

IC50/Ki determination assay protocol

​Pharmacological evaluation of inhibitors of interest can be run in 96- or 384-well plates.

First, a dilution series of inhibitor ranging between 40 µM and 0.23 nM is prepared, and 5 µL of each concentration are dispensed into the plate. Next, 5 µL of tagged-Kinase are added, followed by 5 µL of anti-tag Eu-cryptate. Finally, 5 µL of Sunitinib-Red solution are added, prepared at 4x the final concentration.  The HTRF ratio is measured after 1 H of incubation.

Analyses of the data give  typical dose response curves ranging between 10 µM and 56 pM, enabling an evaluation of the IC50/Ki values for the inhibitor of interest.

Saturation Binding (Kd)

Before perfoming competitive binding studies of inhibitors, the dissociation constant ​(Kd) of Sunitinib-Red has to be determined on the tagged Kinase of interest. This can be done with the help of the Kinase-GST/6HIS/biotin Discovery kits. A typical saturation binding experiment is performed using tracer concentrations between 0 and 250 nM, and measuring total- and non-specific binding signals. Subtracting the non-specific from the total binding signal gives the specific signal, which can be analysed to give the Kd. Here an example is shown for the  determination of the Kd (56 nM) of Sunitinib-Red on 5 nM PDGFRb-GST. ​

Competitive Binding (IC50/Ki)

Dose response curves of various known kinase inhibitors (Staurosporine, Dasatinib, Imatinib, Tozasertib, Sunitinib, and Gefitinib) were measured using Sunitinib-Red at its Kd (56 nM) on 5 nM PDGFRb-GST. Staurosporine, Dasatinib, Sunitinib, and Imatinib show show high potencies in good correlation with literature values. 

3 app notes on kinase inhibitor selection for kinase binding assays

Determine the best tracer to your kinase binding assay - Application Notes

The ultimate guide to successful kinase binding experiments

Tips for getting the best performance from your Kinase binding assay - Guides

Cisbio Product Catalog 2019

All your HTRF assays in one document! - Catalog

A guide to Homogeneous Time Resolved Fluorescence

General principles of HTRF - Guides

Product Insert Sunitinib-red / 62KB03REDC-62KB03REDE

62KB03REDC-62KB03REDE - Product Insert

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