Department of Chemistry
Associate Professor of Chemistry
Ph.D. Kyoto University, 1985
(Bioorganic, Organic, and Biostructural Chemistry)
(206) 543-6590
Email: sasaki@chem.washington.edu
Multivalent carbohydrate-protein and carbohydrate-carbohydrate interactions mediate specific biomolecular recognitions that lead to cell adhesion, inflammatory responses, immune responses and other medicinally important biological processes. In order to understand these recognition events and possibly exploit them for therapeutic purposes, it is essential to develop good methods to produce significant quantities of a diverse variety of multivalent carbohydrate ligands. We have developped a conceptually new approach to rapidly prepare multivalent carbohydrate ligands by the metal-assisted self-assembly process.
The metal-assisted assembly employs a series of bis- and tris-metal complexes as a framework to position multiple carbohydrate residues in a well defined spatial orientation. A combination of monosaccharides generate a vast array of structurally diverse carbohydrate clusters, allowing the development of tools for mapping the carbohydrate binding sites of receptors. Metal-assisted assembly provides us with tools not only to prepare a series of multivalent carbohydrate clusters, but also to determine the affinity of specific pairs of carbohydrate residues. It is difficult to directly measure the binding affinity between two carbohydrate residues in an aqueous solution due to the low association constants. Metal ion can facilitate a controlled aggregation of biopolymers to investigate their interactions that would otherwise be too weak to observe.
We are also collaborating with researchers in the Department of Bioengineering to create new types of biomaterials. Implanted biomaterials are exposed to a mixture of proteins that have distinct shapes and surface functionalities. Since the surface of conventional materials is not well defined both chemically and structurally, these proteins bind to the surface in a random fashion, resulting in the formation of heterogeneous protein layers on the surface. It has been suggested that this heterogeneous protein layer on the surface triggers a series of biological responses that lead to the formation of insulating collagen layers around the material, and eventually to its rejection. We are using template-based approaches to introduce nano-scale patterns on a solid surface that would facilitate the formation of a homogeneous protein layer. Nano-scale patterning of a solid surface could be the basis for the development of future biomaterials that integrate into body tissues.
"Surface characterization of mixed self-assembled monolayers designed for streptavidin immobilization", K. E. Nelson, L. Gamble, L. S. Jung, M. S. Boeckl, E. Naeemi, S. L. Golledge, T. Sasaki, D. G. Castner, C. T. Campbell, P. S. Stayton Langmuir 17, 2807 (2001).
"Catalytic Oxidation of Alkenes with a Surface-Bound Metalloporphyrin-Peptide Conjugate", M. S. Boeckl, A. L. Bramblett, K. D. Hauch, T. Sasaki, B. D. Ratner, J. W. Rogers, Jr. Langmuir 16, 5644 (2000) G. R. Geier III, T. Sasaki, Tetrahedron 55, 1859 (1999).
"On the Absence of Stereoselectivity in the Catalytic Oxidation of Alkenes with a Surface Bound Metalloporphyrin-Peptide Conjugate", G. R. Geier III, T. P. Lybrand, T. Sasaki, Tetrahedron 55, 1871 (1999).
"Iron(II)-assisted Assembly of Trivalent GalNAc Clusters and Their Interactions with GalNAc-specific Lectins", S. Sakai, Y. Shigemasa, T. Sasaki, Bull. Chem. Soc. Jpn 72, 1313 (1999).
"Imprinting for the Assembly of Artificial Receptors on a Solid Surface", K. O. Hwang and T. Sasaki, J. Material Chemistry 8, 2153 (1998)
"Template-Assisted Nano-patterning of Solid Surfaces", M. S. Boeckl, T. Baas, K.-O. Hwang, A. L. Bramblett, B. D. Ratner, J. W. Rogers, T. Sasaki, Biopolymers (Peptide Science) 47, 185 (1998)
"The Synthesis of a Three-Helix Bundle Protein by Reductive Amination", D. C. Tahmassebi, T. Sasaki, J. Org. Chem. 63, 723-731 (1998).
Honorary member, Phi Eta Sigma undergraduate honor society
Nihon Ikuei-Kai Scholarship (graduate)
Nihon Ikuei-Kai Scholarship (undergraduate)