 |
| Born Wellington, New Zealand 1945. |
| Victoria University, B.Sc., 1968. |
| Massey University, M.Sc., 1970. |
| University of California at Berkeley Ph.D., 1975. |
| The Rockefeller University, Research Associate 1974-1977, Assistant Professor 1977-1981. |
| The California Institute of Technology, Senior Research Associate 1983-1989. |
| Bond University, Professor 1989-1990. |
| The Scripps Research Institute, Member & Professor, 1991-1996. |
| Gryphon Sciences, Chief Scientist, 1997-2000. |
| The University of Chicago, Professor, 2001-. |
| Director, Institute for Biophysical Dynamics, 2003-. |
| Joint appointment with the Department of Biochemistry & Molecular Biology. |
| |
| Accolades |
| 2004 Vincent duVigneaud Award, American Peptide Society. |
| 2002 E.T. Kaiser Jr. Award for Innovation in Protein Science, The Protein Society. |
| 2000 Fellow, American Association for the Advancement of Science. |
| 1994 Hirschmann Award in Peptide Chemistry, American Chemical Society. |
| 1968 Senior Scholar, Victoria University. |
|
|
| Stephen B.H. Kent |
| Professor |
|
|
| |
| Research Interests: |
| The Kent research group is devoted to inventing and using new chemistries to reveal how proteins work in nature. To that end, we develop novel methods for the total synthesis of proteins that enable us to apply advanced physical methods in unprecedented ways to understand the chemical basis of protein function. Our goal is to then demonstrate that knowledge by the design and construction of protein molecules with novel properties. |
| |
| Chemical Protein Synthesis |
The total synthesis of natural products is arguably the most important intellectual endeavor in the area of synthetic organic chemistry - it drives methodology forward and generates useful compounds in the process. While landmark small molecule syntheses receive a great deal of attention (and rightly so), it should be recognized that the robust synthesis of large proteins has also been a major goal of organic chemistry since the days of Emil Fischer. Our laboratory invented the chemical ligation methods that now enable the routine total chemical synthesis of protein molecules. Chemical protein synthesis is generally applicable to the efficient preparation of proteins containing 300 or more amino acids. Total synthesis enables the versatile incorporation of non-coded amino acids into proteins, and the modification and labeling of protein molecules, without restriction as to the sites, numbers and kinds of moieties being introduced. Large polypeptides are made by the chemoselective reaction (‘chemical ligation’) of unprotected peptide segments containing unique, mutually reactive functional groups. The most powerful of these chemistries is amide forming thioester-mediated ligation at cysteine residues, termed ‘native chemical ligation’.
 |
| The resulting polypeptide chains are then folded with great efficiency to give high purity synthetic proteins. The covalent structure is confirmed by mass spectrometry and the three dimensional folded structure of the synthetic protein is determined by Xray crystallography. Recently, we introduced ‘kinetically controlled ligation’, a novel and highly sophisticated chemistry for the fully convergent synthesis of large proteins. Currently we are exploring novel chemistries for the synthesis of peptide-thioester building blocks and the use of polymer-supported ligation chemistries for the synthesis of proteins. |
| |
| Chemistry of Enzyme Catalysis |
| We take full advantage of the flexibility provided by total protein synthesis to study the physical organic chemistry of how enzyme molecules work. Backbone engineering of the amide bonds in the polypeptide chain has been used to delete critical H-bonding interactions and to evaluate the effects on enzyme function. 13C & 15N NMR probe nuclei have been introduced at unique single atom sites to elucidate critical aspects of the chemical basis of enzyme catalysis. Single molecule fluorescence spectroscopy is being used to probe the functional properties of uniquely chemical analogues of the enzyme molecule. The chemical synthesis approach enables us to make mirror image enzyme molecules not found in nature. |
The mirror image enzyme HIV-1 protease prepared by total chemical synthesis
{Image credit: Art Olson, TSRI} |
| We are using racemic protein crystallography to determine the Xray structures of proteins that will otherwise not crystallize, and to obtain protein electron density maps of unprecedented accuracy. We are also prototyping ‘mirror image drug discovery’, the use of mirror image enzyme and other protein targets to identify novel lead compounds from chiral natural product small molecule libraries. Synthesis of the enantiomer of the identified compounds will give unique lead molecules effective against the protein found in nature. |
| |
| Synthetic Proteomics and Nanotechnology |
| Proteins are the molecular machines of the living world, performing nearly all of the functions in the cell and playing vital roles in human biology and medicine. In many ways, proteins can be regarded as the most exciting class of natural products of our era. With the success of the genome sequencing projects, proteins are being discovered at an unprecedented rate – a single recent publication described several million novel protein molecules, known only as open reading frame data encoded in the genomic DNA. One of the most pressing challenges of the post-genome era of biomedical research is to understand the structure and function of these predicted protein molecules. The set of synthetic chemistries that we have developed constitute a tool kit for the rapid production of protein molecules based solely on predicted sequence data. In conjunction with advanced mass spectrometry analytical techniques, chemical protein synthesis also enables the precise, facile incorporation of post-translational modifications in controlled fashion for the study of biochemical phenomena such as signal transduction. Additionally, the modular synthesis of protein macromolecules provides powerful tools for the construction of complex nanometer-scale molecular machines. Chemical protein synthesis thus provides a link bridging the world of molecular chemistry to the world of self-assembling nanochemistry for the fabrication of nanoscale devices |
| |
| Selected References |
| Convergent chemical synthesis and crystal structure of a 203 amino acid ‘covalent dimer’ HIV-1 protease enzyme molecule. Angew Chem, Int Ed, 46, 1667-1670 (2007). |
| Selective desulfurization of cysteine in the presence of Cys(Acm) in polypeptides obtained by native chemical ligation. Org Lett, 9, 687-690 (2007). |
| Convergent chemical synthesis and high resolution X-ray structure of human lysozyme. Proc. Natl. Acad. Sci. USA, 104, 4846-4851 (2007). |
| Towards the total chemical synthesis of integral membrane proteins: a general method for the synthesis of hydrophobic peptide-α thioester building blocks. Tetrahedron Lett, 48, 1795-1799 (2007). |
| Studies on the insolubility of a transmembrane peptide from signal peptide peptidase. J. Am. Chem. Soc. 128, 7140-7141 (2006). |
| Insights into the mechanism and catalysis of the native chemical ligation reaction. J. Am. Chem. Soc. 128, 6640-6646 (2006). |
| Kinetically-controlled ligation for the convergent chemical synthesis of proteins. Angew Chem, Int Ed 45, 3985-3988 (2006). |
| Total chemical synthesis, folding, and assay of a small protein on a water-compatible solid support. Angew Chem, Int Ed 45, 3283-3287 (2006). |
| Dissecting the energetics of protein α-helix C-cap termination through chemical protein synthesis. Nature Chemical Biology, 2, 139-143 (2006). |
| Total chemical synthesis and X-ray crystal structure of a protein diastereomer: [D-Gln35] Ubiquitin. Angew. Chem. Int. Ed. Eng., Chem., 44, 3852-3856 (2005). |
| Medicinal chemistry applied to a synthetic protein: development of highly potent HIV entry inhibitors. Proc. Nat. Acad. Sci. USA, 101,16460-16465 (2004). |
| A one-pot chemical synthesis of Crambin. Angew. Chem. Int. Ed. Eng., 43, 2534-8 (2004). |
| Design and chemical synthesis of a homogeneous polymer-modified erythropoiesis protein. Science 299, 884-887 (2003). |
| |
|
Organic Chemistry 