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Madhavi.P, Dr. Hitendra Nath Deka

To radiolabel proteins, peptides, and other biologically sensitive molecules with 18F, using N-succinimidyl 4-fluorobenzoate as a coupling ligand, since it is not possible to directly and rapidly fluorinate these molecules. When synthesizing these molecules with radioactive 18F, the half-life of the radionuclide must be kept in mind. Because of this, the synthesis of these molecules is limited to a few steps, with no need for a final purification step. This is the reason it was decided to tether our analyte molecule on a resin and then couple the linker to the molecule as it is tethered, so that there was a possibility of washing away any contaminants or side products. This improves the likelihood of synthesizing pure products. During this project, Wang resin was used because forms ester bonds with the molecule and it is well-precendented for its use in protein synthesis.Scheme 2 illustrates the multi-step synthesis used to radiolabel the proteins. The protein is first protected with Fmoc-Cl and is then tethered onto the Wang resin. It is subsequently deprotected and then coupled with the linker. Lastly, the molecule is cleaved off of the resin. All of these experiments were done with cold fluorine to develop on the methodology. The resin was purchased from Fisher scientific. All the other reagents were purchased from Sigma Aldrich, including the tripeptides. The 1H NMR was recorded on a 500 MHz Varian instrument and are reported in ppm down field relative to tetramethylsilane as an internal standard. TLC analyses were carried out on general-purpose silica gel on polyester TLC plates and were visualized under UV.