1. Asymmetric synthesis of 3-azide-4-fluoro-l-phenylalanine
Masaatsu Adachi, Mado Nakajima, Minoru Isobe Biosci Biotechnol Biochem. 2015;79(5):707-9. doi: 10.1080/09168451.2014.997185. Epub 2015 Jan 6.
The asymmetric synthesis of N-Fmoc-protected 3-azide-4-fluoro-l-phenylalanine as a photoactive phenylalanine analog has been achieved by Schöllkopf's alkylation.
2. Fluorescence and 19F NMR evidence that phenylalanine, 3-L-fluorophenylalanine and 4-L-fluorophenylalanine bind to the L-leucine specific receptor of Escherichia coli
L A Luck, C Johnson Protein Sci. 2000 Dec;9(12):2573-6. doi: 10.1110/ps.9.12.2573.
The binding capacity of the L-leucine receptor from Escherichia coli was measured with L-phenylalanine and 4-fluoro-L-phenylalanine as substrates by fluorescence. The apparent dissociation constants (KD) for L-leucine, L-phenylalanine, and 4-fluoro-L-phenylalanine are 0.40, 0.18, and 0.26 respectively. 19F NMR data show protein-induced shifts for the 4-fluoro-L-phenylalanine peak and 3-fluoro-L-phenylalanine when receptor is present. Evidence points to the binding of only the L-isomers of these fluorine analogs.
3. Dual effects of [Tyr(6)]-gamma2-MSH(6-12) on pain perception and in vivo hyperalgesic activity of its analogues
Chunnan Wei, Wenmin Huang, Xiaoting Xing, Shouliang Dong J Pept Sci. 2010 Sep;16(9):451-5. doi: 10.1002/psc.1255.
[Tyr(6)]-gamma2-MSH(6-12) with a short effecting time of about 20 min is one of the most potent rMrgC receptor agonists. To possibly increase its potency and metabolic stability, a series of analogues were prepared by replacing the Tyr(6) residue with the non-canonical amino acids 3-(1-naphtyl)-L-alanine, 4-fluoro-L-phenylalanine, 4-methoxy-L-phenylalanine and 3-nitro-L-tyrosine. Dose-dependent nociceptive assays performed in conscious rats by intrathecal injection of the MSH peptides showed [Tyr(6)]-gamma2-MSH(6-12) hyperalgesic effects at low doses (5-20 nmol) and analgesia at high doses (100-200 nmol). This analgesic activity is fully reversed by the kyotorphin receptor-specific antagonist Leu-Arg. For the two analogues containing in position 6, 4-fluoro-L-phenylalanine and 3-nitro-L-tyrosine, a hyperalgesic activity was not observed, while the 3-(1-naphtyl)-L-alanine analogue at 10 nmol dose was found to induce hyperalgesia at a potency very similar to gamma2-MSH(6-12), but with longer duration of the effect. Finally, the 4-methoxy-L-phenylalanine analogue (0.5 nmol) showed greatly improved hyperalgesic activity and prolonged effects compared to the parent [Tyr(6)]-gamma2-MSH(6-12) compound.
