Synthesis of Amino Acids Bearing Halodifluoromethyl Moieties and Their Application to p53-Derived Peptides Binding to Mdm2/Mdm4

• Published in: Drug design, development and therapy Vol. 17; pp. 1247 - 1274
• Main Authors: Vaas, Sebastian, Zimmermann, Markus O, Klett, Theresa, Boeckler, Frank M
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2023; Dove; Dove Medical Press
• Subjects: Amino Acids; Care and treatment; Cell Cycle Proteins; Ethylenediaminetetraacetic acid; fluorescence polarization assay; halogen bonding; Halogens - chemistry; Health aspects; Humans; mdmx; oncological target; Original Research; Peptides; Peptides - chemistry; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-mdm2 - chemistry; solid-phase peptide synthesis; Tumor proteins; Tumor Suppressor Protein p53; unnatural amino acids; United States; Massachusetts; Germany; oncological target; fluorescence polarization assay; solid-phase peptide synthesis; unnatural amino acids; halogen bonding; MdmX
• ISSN: 1177-8881; 1177-8881
• DOI: 10.2147/DDDT.S406703

Therapeutic peptides are a significant class of drugs in the treatment of a wide range of diseases. To enhance their properties, such as stability or binding affinity, they are usually chemically modified. This includes, among other techniques, cyclization of the peptide chain by bridging, modifications to the backbone, and incorporation of unnatural amino acids. One approach previously established, is the use of halogenated aromatic amino acids. In principle, they are thereby enabled to form halogen bonds (XB). In this study, we focus on the -R-CF X moiety (R = O, NHCO; X = Cl, Br) as an uncommon halogen bond donor. These groups enable more spatial variability in protein-protein interactions. The chosen approach via Fmoc-protected building blocks allows for the incorporation of these modified amino acids in peptides using solid-phase peptide synthesis. Using a competitive fluorescence polarization assay to monitor binding to Mdm4, we demonstrate that a p53-derived peptide with Lys24Nle(εNHCOCF X) exhibits an improved inhibition constant K compared to the unmodified peptide. Decreasing K values observed with the increasing XB capacity of the halogen atoms (F ≪ Cl < Br) indicates the formation of a halogen bond. By reducing the side chain length of Nle(εNHCOCF X) to Abu(γNHCOCF X) as control experiments and through quantum mechanical calculations, we suggest that the observed affinity enhancement is related to halogen bond-induced intramolecular stabilization of the α-helical binding mode of the peptide or a direct interaction with His54 in human Mdm4.