Document Type


Publication Date



A number of linear and cyclic peptides containing alternative arginine and cysteine residues, namely linear (CR)3, linear (CR)4, linear (CR)5, cyclic [CR]4, and cyclic [CR]5, were synthesized. The peptides were evaluated for their ability to deliver two molecular cargos, fluorescence-labeled cell-impermeable negatively charged phosphopeptide (F′-GpYEEI) and fluorescence-labeled lamivudine (F′-3TC), intracellularly in human leukemia cancer (CCRF-CEM) cells. We investigated the role of cyclization and the number of amino acids in improving the transporting ability of the peptides. The flow cytometry studies suggested that the synthesized peptides were able to work efficiently as transporters for both cargos. Among all compounds, cyclic [CR]4 was found to be the most efficient peptide in transporting the cargo into cells. For instance, the cellular uptake of F′-3TC (5 μM) and F′-GpYEEI (5 μM) was enhanced by 16- and 20-fold, respectively, in the presence of cyclic [CR]4 compared to that of the parent compound alone. The mechanism of F′-GpYEEI uptake by cells was found to be energy-independent. The results showed that the number of amino acids and their cyclic nature can impact the efficiency of the peptide in transporting the molecular cargos.


NOTICE: this is the author’s version of a work that was accepted for publication in Bioorganic & Medicinal Chemistry Letters in 2015. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version will be subsequently published in Bioorganic & Medicinal Chemistry Letters. DOI: 10.1016/j.bmcl.2015.11.052

The Creative Commons license below applies only to this version of the article.



Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.