- Total Chemical Synthesis and Folding of All- l and All- d Variants of Oncogenic KRas(G12V)
-
The Ras proteins are essential GTPases involved in the regulation of cell proliferation and survival. Mutated oncogenic forms of Ras alter effector binding and innate GTPase activity, leading to deregulation of downstream signal transduction. Mutated forms of Ras are involved in approximately 30% of human cancers. Despite decades of effort to develop direct Ras inhibitors, Ras has long been considered "undruggable" due to its high affinity for GTP and its lack of hydrophobic binding pockets. Herein, we report a total chemical synthesis of all-l- and all-d-amino acid biotinylated variants of oncogenic mutant KRas(G12V). The protein is synthesized using Fmoc-based solid-phase peptide synthesis and assembled using combined native chemical ligation and isonitrile-mediated activation strategies. We demonstrate that both KRas(G12V) enantiomers can successfully fold and bind nucleotide substrates and binding partners with observable enantiodiscrimination. By demonstrating the functional competency of a mirror-image form of KRas bound to its corresponding enantiomeric nucleotide triphosphate, this study sets the stage for further biochemical studies with this material. In particular, this protein will enable mirror-image yeast surface display experiments to identify all-d peptide ligands for oncogenic KRas, providing a useful tool in the search for new therapeutics against this challenging disease target.
- Levinson, Adam M.,McGee, John H.,Roberts, Andrew G.,Creech, Gardner S.,Wang, Ting,Peterson, Michael T.,Hendrickson, Ronald C.,Verdine, Gregory L.,Danishefsky, Samuel J.
-
supporting information
p. 7632 - 7639
(2017/06/13)
-
- Solution phase synthesis of β-peptides using micro reactors
-
The synthesis of β-peptides has been successfully performed using a borosilicate glass micro reactor, in which a network of channels has been produced using a photolithographic and wet etching method. The reagents were mobilised by electroosmotic flow (EOF). The micro reactor was initially evaluated using a carbodiimide coupling reaction to form a dipeptide. The methodology has been extended such that the peptides may also be produced via the pentafluorophenyl ester derivatives of amino acids. It was found that performing the pentafluorophenyl ester reactions in the micro reactor resulted in an increase in the reaction efficiency over the traditional batch method. We postulate that the enhancement in rate of reaction is an electrochemical phenomenon, due to the reaction being performed in an electric field, which is unique to micro reactor systems. It has also been demonstrated that selective deprotection of the resultant dipeptides can be achieved. This approach has been used in the synthesis of a tripeptide.
- Watts, Paul,Wiles, Charlotte,Haswell, Stephen J,Pombo-Villar, Esteban
-
p. 5427 - 5439
(2007/10/03)
-