Page - (000312) - in Biomedical Chemistry: Current Trends and Developments

15 H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-NH2 0.3 ± 0.0 16 H-Tyr-Pro-Phe-Phe-OH 30.2 ± 1.7 Truncated SP1–7 Peptides 17 H-Pro-Lys-Pro-Gln-Gln-Phe-OH 29.6 ± 0.8 18 H-Pro-Lys-Pro-Gln-Gln-Phe-NH2 2.8 ± 0.25 19 H-Lys-Pro-Gln-Gln-Phe-OH 30.9 ± 0.4 20 H-Lys-Pro-Gln-Gln-Phe-NH2 4.4 ± 0.1 21 H-Pro-Gln-Gln-Phe-OH 26.2 ± 0.7 22 H-Pro-Gln-Gln-Phe-NH2 4.5 ± 0.3 23 H-Gln-Gln-Phe-OH 20.4 ± 0.8 24 H-Gln-Gln-Phe-NH2 1.9 ± 0.05 Truncated EM-2 Peptides 25 H-Pro-Phe-Phe-NH2 10.9 ± 0.7 26 H-Phe-Phe-NH2 1.5 ± 0.1 27 H-Phe-NH2 5028 ± 31 The results were remarkably consistent for SP1–7 and EM-2 peptides (Table 3.3.3). Substitution with alanine in the N-terminal part of SP1–7 was well tolerated without affecting the binding affinity significantly (cf. 1 with 4, 5 and 6), although replacement of the basic amino acid arginine rendered a 10-fold lower affinity (cf. 1 and 3). Likewise, the three N-terminal amino acid residues in EM-2 (tyrosine, proline and the internal phenylalanine) could be substituted with an alanine and still retain binding affinity (cf. 2 with 10, 11 and 12). However, removal of the