Protein – Peptide Interactions
A good example of how PCL has used fluorescence anisotropy to quantify a protein-peptide binding interaction was in collaboration with Dr. Terry Burke Jr. (Chemical Biology Laboratory, CCR, NCI) and Dr. Eric Freed (HIV Drug Resistance Program, CCR NCI). The HIV Gag protein contains a PTAP (Pro-Thr-Ala-Pro) peptide motif that specifically interacts with the human protein Tsg101 (tumor susceptibility gene 101), a component of the cellular export machinery that enables HIV to escape from infected cells. Agents that block this interaction would be of therapeutic interest. In this collaboration Dr. Burke’s laboratory developed a series of peptidomimetics of the PTAP motif and the PCL evaluated their binding to Tsg101 protein by fluorescence anisotropy.
The figure below shows the binding of Tsg101 to the wild type PTAP peptide with a KD of 70 nM compared to the binding of the most potent peptidomimetic with a KD of 5 nM.