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To investigate the role of peptide backbone conformation on the biological activity of chemotactic peptides, we synthesized a unique analog of N-formyl-Met-Leu-Phe-OH incorporating the C alpha,alpha disubstituted residue, dipropylglycine (Dpg) in place of Leu. The conformation of the stereochemically constrained Dpg analog was examined in the crystalline state by x-ray diffraction and in solution using NMR, IR, and CD methods. The secretagogue activity of the peptide on human neutrophils was determined and compared with that of a stereochemically constrained, folded type II beta-turn analog incorporating 1-aminocyclohexanecarboxylic acid (Ac6c) at position 2 (f-Met-Ac6c-Phe-OMe), the parent peptide (f-Met-Leu-Phe-OH) and its methyl ester derivative (f-Met-Leu-Phe-OMe). In the solid state, the Dpg analog adopts an extended beta-sheet-like structure with an intramolecular hydrogen bond between the NH and CO groups of the Dpg residue, thereby forming a fully extended (C5) conformation at position 2. The phi and psi values for Met and Phe residues are significantly lower than the values expected for an ideal antiparallel beta conformation causing a twist in the extended backbone both at the N and C termini. Nuclear magnetic resonance studies suggest the presence of a significant population of the peptide molecules in an extended antiparallel beta conformation and the involvement of Dpg NH in a C5 intramolecular hydrogen bond in solutions of deuterated chloroform and deuterated dimethyl sulfoxide. IR studies provide evidence for the presence of an intramolecular hydrogen bond in the molecule and the antiparallel extended conformation in chloroform solution. CD spectra in methanol, trifluoroethanol, and trimethyl phosphate indicate that the Dpg peptide shows slight conformational flexibility, whereas the folded Ac6c analog is quite rigid. The extended Dpg peptide consistently shows the highest activity in human peripheral blood neutrophils, being approximately 8 and 16 times more active than the parent peptide and the folded Ac6c analog, respectively. However, the finding that all four peptides have ED50 (the molar concentration of peptide to induce half-maximal enzyme release) values in the 10(-8)-10(-9) M range suggests that an induced fit mechanism may indeed be important in this ligand-receptor interaction. Moreover, it is also possible that alterations in the backbone conformation at the tripeptide level may not significantly alter the side chain topography and/or the accessibility of key functional groups important for interaction with the receptor.
References
- Biochem. Biophys. Res. Commun. 1977; 74: 810-817
- Int. J. Peptide Protein Res. 1982; 19: 133-136
- Int. J. Peptide Protein Res. 1985; 25: 628-639
- Am. J. Pathol. 1987; 129: 16-24
- Biochemistry. 1979; 18: 4656-4668
- Int. J. Immunopharmacol. 1989; 11: 467-471
- J. Am. Chem. Soc. 1984; 106: 8146-8152
- Fasman G.D. Poly-α-amino Acids. 1. Marcel Dekker Inc., New York1967: 293-337
- J. Mol. Biol. 1982; 155: 321-346
- Int. J. Peptide Protein Res. 1985; 26: 482-492
- J. Am. Chem. Soc. 1984; 106: 8152-8156
- Biochem. Biophys. Res. Commun. 1990; 168: 1103-1109
- Nuclear Magnetic Resonance Spectroscopy. Academic Press, San Diego1988
- J. Mol. Biol. 1973; 75: 295-302
- Int. J. Peptide Protein Res. 1984; 23: 411-419
- J. Mol. Biol. 1988; 201: 161-200
- Mol. Immunol. 1985; 22: 463-475
- Int. J. Peptide Protein Res. 1988; 31: 164-172
- Acta Crystallogr. Sect. C Cryst. Struct. Commun. 1990; 46: 1314-1318
- Int. J. Peptide Protein Res. 1989; 34: 229-234
- Biochemistry. 1982; 21: 257-263
- Biochemistry. 1980; 19: 2404-2410
- Structure Determination Package. Enraf-Nonius, Delft, Holland1985
- Int. J. Peptide Protein Res. 1989; 34: 409-415
- Int. J. Peptide Protein Res. 1983; 21: 392-405
- Biochem. J. 1990; 268: 249-262
- FEBS Lett. 1984; 165: 171-174
- Biochemistry. 1970; 9: 3471-3479
Johnson, C. K. (1965) ORTEP Report ORNL-3794, Oak Ridge National Laboratory, Tennessee
- Acta Crystallogr. Sect. B Struct. Sci. 1983; 39: 625-637
- J. Am. Chem. Soc. 1988; 110: 1958-1963
- Int. J. Peptide Protein Res. 1989; 34: 37-41
- J. Am. Chem. Soc. 1973; 85: 2870-2871
- Angew. Chem. Int. Ed. Engl. 1982; 21: 512-523
- Chem. Ber. 1970; 103: 788-798
- J. Am. Chem. Soc. 1972; 94: 3644-3646
- Adv. Protein Chem. 1986; 38: 181-364
- Biophys. J. 1980; 32: 807-836
- Science. 1990; 250: 669-673
- Laboratory Manual of Neutrophil Function. Raven Press, New York1986
- Fasman G.D. Poly-α-amino Acids. 1. Marcel Dekker Inc., New York1967: 69-103
- Cryst. Struct. Commun. 1981; 10: 781-788
- Biochem. Biophys. Res. Commun. 1969; 36: 194-202
- J. Mol. Biol. 1984; 180: 741-751
- J. Am. Chem. Soc. 1972; 94: 1399-1400
- Biopolymers. 1985; 24: 1131-1146
- J. Indian Inst. Sci. 1986; 66: 342-345
- Biopolymers. 1990; 30: 73-85
- Biopolymers. 1988; 27: 683-701
- J. Am. Chem. Soc. 1983; 105: 7423-7428
- Adv. Protein Chem. 1981; 34: 167-339
- J. Mol. Biol. 1981; 146: 101-117
- Proc. Natl. Acad. Sci. U. S. A. 1975; 72: 1059-1062
- Biochem. Biophys. Res. Commun. 1988; 157: 569-574
- Sheldrick G.M. Kruger C. Goodard R. Crystallographic Computing 3. Oxford University Press, New York1985: 175-189
- J. Exp. Med. 1976; 143: 1154-1169
- Biochem. Biophys. Res. Commun. 1985; 128: 339-344
- CRC Crit. Rev. Biochem. 1980; 9: 1-44
- Biopolymers. 1989; 28: 247-257
- ISI Atlas Sci. Biochem. 1988; 1: 225-230
- Can. J. Chem. 1976; 54: 70-76
- Peptides. 1989; 9: 1195-1205
- Peptide Res. 1989; 2: 275-281
- Int. J. Peptide Protein Res. 1986; 28: 334-341
- Proc. Natl. Acad. Sci. U. S. A. 1977; 74: 1204-1208
- NMR in Biological Research: Peptides and Proteins. North Holland, Amsterdam1976
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Published online: October 05, 1991
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© 1991 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.
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