Biophysical Chemistry/Organic Chemistry
Bioactive peptide design and synthesis, protein engineering, ligand-receptor interactions
A major objective of the lab is the development of approaches to understanding the functional conformations of intermediate-sized, flexible peptides with important biological activities. Our basic approach to this problem is the design, synthesis and study of peptide analogues. New methods in solid-phase peptide synthesis are being developed in order to synthesize peptides that are constrained in particular conformations by multiple side-chain to side-chain bridges. For example, lactam bridges linking lysine and aspartic acid residues in i and i+4 positions in the peptide chain are being used to stabilize amphiphilic alpha-helical structures in the peptide hormones beta-endorphin and calcitonin, as well as DNA-binding helical structures such as the basic region from the transcription factor GCN4. More complex structures of this type, simultaneously linking three or four side-chains, are also under development. An important aspect of our strategy is the use of detailed analyses of peptide conformations, by circular dichroism and NMR methods, and of receptor affinities, in order to evaluate the structural and energetic effects of our conformational constraints. In an extension of these studies, we are also investigating helix-stabilized analogues of the transmembrane domains of peptide hormone receptors. The goal of this work is to characterize the helix-helix interactions that define the core of the folded structures of this important class of proteins. Initially, this area of research is focused on the human receptors for opioid peptides such as beta-endorphin, dynorphin and the enkephalins.
Kazantzis, A., Waldner, M, Taylor, J. W., and Kapurniotu, A.: Conformationally constrained human calcitonin (hCt) analogues reveal a critical role of sequence 17-21 for the oligomerization state and bioactivity of hCt. Submitted for publication
Taylor, J. W., Jin, Q. K., Sbacchi, M., Wang, L., Belfiore, P., Garnier, M., Kazantzis, A., Kapurniotu, A., Zaratin, P. F. and Scheideler, M. A.: Side-chain lactam-bridge conformational constraints differentiate the actions of salmon and human calcitonins and reveal a new design concept for potent calcitonin analogs. Submitted for publication.
Zhang, M., Wu, B., Zhao, H. and Taylor, J. W.: The effect of C-terminal helix stabilization on specific DNA binding by monomeric GCN4 peptides. Submitted for publication.
Tian, Y., Ramesh, C.V., Ma, X., Patel, T., Tiscione, M., Cenizal, T., Taylor, J.W.; Arnold, G.F., and Arnold, E.: Affinity of the HIV-1-neutralizing monoclonal antibody 2F5 for gp41 ELDKWA peptide analogues. In: Peptides: The Wave of the Future; Proc. 2nd International / 17th American Peptide Symposium (G. Barany, G. B. Fields, R. A. Houghten & M. Lebl, eds.), manuscript accepted, June, 2001.
Taylor, J.W., Reddy, P., Patel, P. Dineen, T., and Naqvi, S.: Novel synthesis and application of a protected bicyclic a-helix-initiating heptapeptide suitable for segment condensation syntheses: Utility of pentaaminecobalt(III) for carboxyl protection. In: Peptides: The Wave of the Future; Proc. 2nd International / 17th American Peptide Symposium (G. Barany, G. B. Fields, R. A. Houghten & M. Lebl, eds.), manuscript accepted, June, 2001
M. Zhang, B. Wu, J. Baum, and J. Taylor. "Conformational Characterization of a Helix-Nucleated Bicyclic GCN4 Decapeptide by Proton NMR", Journal of Peptide Research, 55, 398-408, 2000.
Xie, L., and Taylor, J. W. Synthetic peptides designed to probe the structure and folding of opioid receptors. Proc. 16th Amer. Peptide Symp. (G. B. Fields, J. P. Tam & G. Barany, eds.), Kluwer Academic Publishers, Boston, 2000, pp.372-373.
Taylor, J. W., Greenfield, N. J., Wu, B., Yu, Y. B. and Privalov, P. A calorimetric study of the helix-coil transition using a side-chain bridged peptide that folds and unfolds cooperatively. Proc. 16th Amer. Peptide Symp. (G. B. Fields, J. P. Tam & G. Barany, eds.), Kluwer Academic Publishers, Boston, 2000, pp 280-282
Zhang, M., Yu, C., Baum, J. and Taylor, J. W. 1H-NMR structure of a model 14-residue peptide incorporating a rigid, helix-stabilizing, (i, i+7)-side-chain bridge. Proc. 16th Amer. Peptide Symp. (G. B. Fields, J. P. Tam & G. Barany, eds.), Kluwer Academic Publishers, Boston, 2000, pp. 283-284.
Yu, C. and Taylor, J. W.: Synthesis and study of peptides with semirigid i and i+7 side-chain bridges designed for a-helix stabilization. Bioorg. Med. Chem. 7, 161-175, 1999.
Taylor, J. W., Greenfield, N. J., Wu, B. and Privalov, P. A calorimetric study of the unfolding of an alpha-helix with covalently closed N- and C-terminal loops. J. Mol. Biol. 291, 965-976, 1999.
Kayed, R., Taylor, J. W., Voelter, W. and Kapurniotu, A.: Rational design, conformational studies and bioactivity of highly potent, conformationally constrained calcitonin analogues. Eur. J. Biochem. 265, 606-618, 1999.
Zhang, W. and Taylor, J. W.: Efficient solid-phase synthesis of peptides with tripodal side-chain bridges and optimization of the solvent conditions for solid-phase cyclizations. Tetrahedron Lett. 37, 2173-2176, 1996
Yu, C. and Taylor, J. W.: A new strategy applied to the synthesis of an a-helical bicyclic peptide constrained by two overlapping i, i+7 side-chain bridges of novel design. Tetrahedron Lett. 37, 1731-1734, 1996.
Kapurniotu, A. and Taylor, J. W.: Structural and conformational requirements for human calcitonin activity: design, synthesis and study of lactam-bridged analogues. J. Med. Chem. 38, 836-847 1995.
Bracken, C., Guly�s, J., Taylor, J. W. and Baum, J.: Synthesis and NMR structure determination of an alpha-helical, bicyclic, lactam-bridged hexapeptide. J. Amer. Chem. Soc., 116, 6431-6432, 1994.
Flach, C. R., Brauner, J. W., Taylor, J. W., Baldwin, R. C. and Mendelsohn, R.: External reflection FT-IR of peptide monolayer films in situ at the air/water interface: Experimental design, spectra-structure correlations and effects of hydrogen-deuterium exchange. Biophys. J., 67, 402-410, 1994.
Taylor, J. W., Shih, I.-L., Lees, A. M. and Lees, R. S.: Surface-induced conformational switching in amphiphilic peptide segments of Apolipoproteins B and E and model peptides. Int. J. Peptide Protein Res., 41, 536-547, 1993.