NIU Department of
Chemistry & Biochemistry
Where the study of matter...matters!
Office: La Tourette Hall 428
Phone: (815) 753-6898
Postdoctoral Fellow, Weizmann Institute of Science, 1999-2000
Dr. rer. nat., Eberhard-Karls-Universität Tübingen, 1999
M.S., Eberhard-Karls-Universität Tübingen, 1995
B.S., Eberhard-Karls-Universität Tübingen, 1991
Biorecognition; immunochemistry; chiral separations; affinity techniques and sensors.
Antibodies as tailor-made chiral selectors for detection and separation of stereoisomers. Hofstetter, H.; Hofstetter, O. (2005) Trends Anal. Chem., 24: 869–879.
New developments in the production and use of stereose-lective antibodies. Hofstetter, H.; Cary, J. R.; Eleniste, P. P.; Hertweck, J. K.; Lindstrom, H. J.; Ranieri, D. I.; Smith, G. B.; Undesser, L. P.; Zeleke, J. M.; Zeleke, T. K.; Hofstetter, O. (2005) Chirality, 17: S9–S18.
Magnetic relaxation switch immunosensors detect enantiomeric impurities. Tsourkas, A.; Hofstetter, O.; Hofstetter, H.; Weissleder, R.; Josephson, L. (2004) Angew. Chem. Int. Ed., 43: 2395–2399.
Enantioselective sensors based on antibody-mediated nanomechanics. Dutta, P.; Tipple, C. A.; Lavrik, N. V.; Datskos, P. G.; Hofstetter, H.; Hofstetter, O.; Sepaniak, M. J. (2003) Anal. Chem., 75: 2342-2348.
Direct resolution of enantiomers in high- performance immunoaffinity chromatography under isocratic conditions. Hofstetter, O.; Lindstrom, H.; Hofstetter, H. (2002) Anal. Chem., 74: 2119-2125.
An immunochemical approach for the determination of trace amounts of enantiomeric impurity. Hofstetter, O.; Hofstetter, H.; Wilchek, M.; Schurig, V.; Green, B. S. (2000) Chem. Commun., 1581-1582.
Chiral discrimination using an immunosensor. Hofstetter, O.; Hofstetter, H.; Wilchek, M.; Schurig, V.; Green, B. S. (1999) Nature Biotechnol., 17: 371-374.
Antibodies can recognize the chiral center of free -amino acids. Hofstetter, O.; Hofstetter, H.; Schurig, V.; Wilchek, M.; Green, B. S. (1998) J. Am. Chem. Soc., 120: 3251-3252.
Physiological processes invariably depend on specific interactions between biological binding partners. Since receptors, enzymes, and antibodies are able to differentiate between the stereoisomers of chiral compounds, one stereoisomer is generally preferred in, for example, metabolic pathways, intra- and intercellular communication, and as a building block for the formation of macromolecules. Thus, living organisms discriminate between the enantiomers of exogenous compounds (e.g., drugs) at virtually all levels of interaction, and respond differently to them. Even minor enantiomeric impurities may cause severe pharmacological and toxicological side effects. The development of refined analytical techniques and selectors for the precise determination of biologically relevant chiral molecules, and their purification, is therefore of great interest.
My research focuses on the production of stereoselective antibodies and their application as "tailor-made" chiral selectors in affinity techniques. Recently, polyclonal and monoclonal antibodies, which stereoselectively bind either to D- or L--amino acids, were produced. These antibodies are "group-specific"; that is, they recognize the -amino acid functional group, the hydrogen/carboxyl/amino triad, whereas the side chain is of minor importance for binding.
The exquisite stereoselectivity of the antibody-antigen interaction, as depicted in the schematic below, allows the detection of enantiomeric impurities in enzyme immunoassays and sensor systems at a level of sensitivity that exceeds all currently available methods. We also apply antibodies in pressure- and electrodriven chromatographic techniques for the analytical and preparative separation of chiral compounds. An important aspect of this research is the development of miniaturized systems and high-throughput assays.
Schematic depiction of immobilized antibodies and their stereoselective interaction with a chiral compound. The chromatogram at right shows the separation profile of the enantiomers using HPLC.
Research in my laboratory is interdisciplinary and combines aspects of immunology, protein chemistry, analytical chemistry, and molecular biology.