Nitrodibenzofuran: A One- and Two-Photon Sensitive Protecting Group That Is Superior to Brominated Hydroxycoumarin for Thiol Caging in Peptides.

Abstract

Photoremovable protecting groups are important for a wide range of applications in peptide chemistry. Using Fmoc-Cys(Bhc-MOM)-OH, peptides containing a Bhc-protected cysteine residue can be easily prepared. However, such protected thiols can undergo isomerization to a dead-end product (a 4-methylcoumarin-3-yl thioether) upon photolysis. To circumvent that photoisomerization problem, we explored the use of nitrodibenzofuran (NDBF) for thiol protection by preparing cysteine-containing peptides where the thiol is masked with an NDBF group. This was accomplished by synthesizing Fmoc-Cys(NDBF)-OH and incorporating that residue into peptides by standard solid-phase peptide synthesis procedures. Irradiation with 365 nm light or two-photon excitation with 800 nm light resulted in efficient deprotection. To probe biological utility, thiol group uncaging was carried out using a peptide derived from the protein K-Ras4B to yield a sequence that is a known substrate for protein farnesyltransferase; irradiation of the NDBF-caged peptide in the presence of the enzyme resulted in the formation of the farnesylated product. Additionally, incubation of human ovarian carcinoma (SKOV3) cells with an NDBF-caged version of a farnesylated peptide followed by UV irradiation resulted in migration of the peptide from the cytosol/Golgi to the plasma membrane due to enzymatic palmitoylation. Overall, the high cleavage efficiency devoid of side reactions and significant two-photon cross-section of NDBF render it superior to Bhc for thiol group caging. This protecting group should be useful for a plethora of applications ranging from the development of light-activatable cysteine-containing peptides to the development of light-sensitive biomaterials.

• Authors: M Mohsen Mahmoodi, Daniel Abate-Pella, Tom J Pundsack, Charuta C Palsuledesai, Philip C Goff, David A Blank, Mark D Distefano
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 138 Issue 18 Pg. 5848-59 (05 11 2016) ISSN: 1520-5126 [Electronic] United States
• PMID: 27027927 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• Benzofurans
• Coumarins
• Indicators and Reagents
• Peptides
• Sulfhydryl Compounds
• 3-nitrodibenzofuran
• Farnesyl-Diphosphate Farnesyltransferase
• Cysteine

Topics

• Antineoplastic Agents (chemical synthesis, pharmacology)
• Benzofurans (chemistry)
• Cell Line, Tumor
• Cell Membrane (metabolism)
• Coumarins (chemistry)
• Cysteine (chemistry)
• Cytosol (metabolism)
• Farnesyl-Diphosphate Farnesyltransferase (antagonists & inhibitors)
• Female
• Golgi Apparatus (metabolism)
• Halogenation
• Humans
• Indicators and Reagents
• Ovarian Neoplasms (drug therapy)
• Peptides (chemical synthesis, chemistry, pharmacology)
• Photochemical Processes
• Photons
• Solid-Phase Synthesis Techniques
• Sulfhydryl Compounds (chemistry)