The unnatural amino acid Aca (7-amino-coumarin-4-acetic acid) is a coumarin derivative and thus exhibits fluorescence. When incorporated into a peptide C-terminally of phenylalanine, Aca is a useful reporter group for the successful internalization of CPPs. The phenyl moiety of Phe quenches the fluorescence of Aca. Internalization of the CPP containing Phe-Aca leads to proteolytic cleavage of the Phe-Aca bond and thus to fluorescence.

However, the peptide bond formation between Phe and Aca is considered to be a difficult coupling and often leads to low coupling yields. For your convenience, Iris Biotech offers Fmoc Phe-Aca as building block suitable for SPPS. This pseudodipeptide can be coupled to the resin of your choice and subsequently elongated to prepare your target cell penetrating peptides.

• → Find many different Resins for SPPS in our Iris Biotech Webshop.
• → Do you require Coupling Reagents or Solvents for SPPS? Find everything you need and more in our Reagents section.
• → Iris Biotech offers both common and unusual Amino Acid building blocks.
• → For your convenience, we also offer all 20 standard Fmoc-amino acids as pre-packed cartridges for ABI, CEM and PTI peptide synthesizers.

References:

• Rapid and general profiling of protease specificity by using combinatorial fluorogenic substrate libraries; J. L. Harris, B. J. Backes, F. Leonetti, S. Mahrus, J. A. Ellman and C. S. Craik; Proceedings of the National Academy of Sciences 2000; 97: 7754-7759. doi:10.1073/pnas.140132697
• Expedient Solid-Phase Synthesis of Fluorogenic Protease Substrates Using the 7-Amino-4-carbamoylmethylcoumarin (ACC) Fluorophore; D. J. Maly, F. Leonetti, B. J. Backes, D. S. Dauber, J. L. Harris, C. S. Craik and J. A. Ellman; The Journal of Organic Chemistry 2002; 67: 910-915. doi:10.1021/jo016140o