David E. Hansen

Professor of Chemistry, Amherst College

Email: dehansen@amherst.edu
D. Hansen Chemistry Dept Website

Ph.D.: Harvard University
Honors: Camille and Henry Dreyfus Teacher-Scholar Award; National Science Foundation Presidential Young Investigator Award

Bioorganic Chemistry: Isolation of Novel Antibody Catalysts

Our principal interest is the isolation of monoclonal antibodies with sequence-specific peptidase and, ultimately, protease activity. Such antibodies have potential for use in the treatment of diseases in which foreign peptides or proteins are exposed to circulating antibodies and may find application in a variety of biochemical analyses. At present, no general method for generating antibody peptidases or proteases has been developed, and thus, we are exploring new approaches. One strategy is to elicit antibodies against transition state analogues in which the peptide bond mimicked has also been distorted—either through ring or torsional strain—into a reactive conformation. Antibodies raised against these derivatives may effect catalysis by both destabilizing the bound peptide substrate and stabilizing the transition state. Sequence-specificity is achieved by flanking the dipeptide analogues with additional amino-acid residues.

In collaboration with R.A. Goldsby, P.B. O’Hara, and D.I. Ratner, we have also begun studying antibodies isolated from germinal centers, the locus of affinity maturation. Enormous antibody diversity is created within germinal centers, followed by a process of intense selection for maximal binding to immunogen. Recent work has demonstrated that catalytic activity can actually decrease as a result of affinity maturation and that amino-acid residues critical for catalysis can play no role in binding of the immunizing hapten. Both of these observations suggest that antibodies generated early in an immune response, but subsequently lost during affinity maturation, may possess enhanced catalytic activities. By interrupting the immune response, our goal is to isolate these antibodies, which we will then fully characterize.

Representative Publications:

Thierry Pauyo , Gerard J. Hilinski , Philip T. Chiu , David E. Hansen, Yoon J. Choi, David I. Ratner, Nalini Shah-Mahoney, Cathrine A. Southern, and Patricia B. O'Hara, “Genetic and Fluorescence Studies of Affinity Maturation in Related Antibodies,” Molecular Immunology 2005 , accepted for publication.

David E. Hansen, Dengda Tang , Jon A. Sanborn, and Mark D. Marshall, “(Strept)Avidin-Biotin: Two Interrelated Experiments for the Introductory Chemistry Laboratory,” Journal of Chemical Education 2005 , accepted for publication.

Michael L. Dougan , Jonathan L. Chin , Ken Solt , and David E. Hansen, “Rapid cleavage of cyclic tertiary amides of Kemp's triacid: effects of ring structure,” Bioorganic and Medicinal Chemistry Letters 2004 , 14 , 4153-4156.

Hansen, D.E., Roberts, R.A., Wang, Z., Plourde, R. and Sugasawara, R.J. (2001) RJS8-1, Mouse Monoclonal to FK-520 (Anti-Ascomycin). Hybridoma 23, 207-208.

Wang, Z., Raifu, M., Howard, M., Smith, L., Hansen, D., Goldsby, R., and Ratner, D. (2000) Universal PCR amplification of mouse immunoglobulin gene variable regions: the design of degenerate primers and an assessment of the effect of DNA polymerase 3' to 5' exonuclease activity. J. Immunol. Methods, 233, 167-177.

Smith, R.M. and Hansen, D.E. (1998) The pH-Rate Profile for the Hydrolysis of a Peptide Bond. J. Am. Chem. Soc. 120, 8910-8913.

Bryant, R.A.R. and Hansen, D.E. (1996) Direct Measurement of the Uncatalyzed Rate of Hydrolysis of a Peptide Bond. J. Am. Chem. Soc. 118, 5498-5499.

Smith, R.M., Weiner, D.P., Chaturvedi, N.C., Thimblin, Jr., M.D., Raymond, S.J. and Hansen, D.E. (1995) Norbornyl Dipeptide Analogues: Mimics of Both a Transition State and a Torsionally-Distorted Ground State. Bioorg. Chem. 23, 397-414.

Yuan, P., Plourde, R., Shoemaker, M.R., Moore, C.L. and Hansen, D.E. (1995) A Mimic of Both a Torsionally-Distorted Peptide Ground State and the Transition State for Peptide Bond Hydrolysis: Synthesis of a Spiro[4.4]nonyl Derivative. J. Org. Chem. 60, 5360-5364.

Yuan, P., Driscoll, M.D., Raymond, S.J., Hansen, D.E. and Blatchly, R.A. (1994) The Synthesis of Cyclobutanol-Containing Dipeptide Analogues. Tetrahedron Lett. 35, 6195-6198.