A novel molecular tool for photoaffinity labeling

February 22, 2018

A less hydrophobic and compact photoreactive group

The RIKEN Synthetic Organic Chemistry Laboratory, RIKEN CSRS, Kyushu University and Keio University have collaboratively developed a new molecular tool, 2-thienyl–substituted α-ketoamide, for use with photoaffinity labeling (PAL).

PAL is an indispensable technique in chemical biology for identifying binding proteins of bioactive molecules. In PAL, the photoreactive group forms a covalent bond with binding proteins by irradiation of UV-light. Conventional photoreactive groups require a hydrophobic and bulky structure to have sufficient reactivity, which results in the disadvantage of forming nonspecific covalent bonds with proteins other than the true binding protein(s).

Thinking that the structure of α-ketoamide could be used as a photoreactive group, the research group linked α-ketoamide to mannose for the proof of concept study, then carried out a photoaffinity labeling experiment with the protein concanavalin A (binding protein of mannose).

Results showed that 2-thienyl-substituted α-ketoamide demonstrated good reactivity and functions well as a photoreactive group. This new photoreactive group was also found to be less hydrophobic than conventional photoreactive groups and compact in size, with significantly suppressed nonspecific binding.

The results indicate this PAL tool holds promise not only for use with biologically active natural products and drugs, but also for analyses of interactions among a wide variety of molecules such as peptides, proteins, sugar chains, nucleic acids, and lipids. Further investigation into the effects of the thienyl group is also expected to lead to the development of even more high-functioning photoreactive groups.

Original article
ACS Chemical Biology doi:10.1021/acschembio.7b00988
E. Ota, K. Usui, K. Oonuma, H. Koshino, S. Nishiyama, G. Hirai, M. Sodeoka,
"Thienyl-substituted α-Ketoamide: A Less Hydrophobic Reactive Group for Photo-Affinity Labeling".
Go Hirai; Visiting Scientist
Mikiko Sodeoka; Group Director
Catalysis and Integrated Research Group