Team:UNIK Copenhagen/Quenchibodies

The second approach is the construction of a fluorescent antibody fragment (FAB) by covalently linking a fluorophore to the N-terminus. A FAB fragment consisting of a heavy- and light-chain part is the N-terminus of an antibody, containing both a variable and a conserved region. The variable region recognizes and binds to the antigen while the conserved region add stability to the FAB. Light emission from the attached fluorophore is quenched by tryptophan residues in the FAB fragment. Upon binding of the antigen, the FAB fragment undergoes structural changes, which displace the fluorophore away from the tryptophan residues eliminating the quenching effect. In this way binding of the antigen results in fluorescence.

Estradiol and progesterone are both environmentally damaging hormones, which in excess are environmentally hazardous due to interference with the reproductive systems of animals, and can lead to various types of cancer including breast and uterus cancer. In this year´s iGEM competition we will construct two fluorescent detection FAB fragments. The FAB fragments will be derived from antibodies binding to the sex hormones estradiol and progesterone. These products will thus allow for fast and easy detection of the levels of both hormones. This work is inspired by (Abe et al., 2014).

References:
Abe, R., Jeong, H.-J., Arakawa, D., Dong, J., Ohashi, H., Kaigome, R., … Ueda, H. (2014). Ultra Q-bodies: quench-based antibody probes that utilize dye-dye interactions with enhanced antigen-dependent fluorescence. Scientific Reports, 4, 4640. doi:10.1038/srep04640