DESCRIPTION (provided by applicant): A commercially available instrument for quantitative surface plasmon resonance detection of macromolecular complexes and recovery of molecular components is requested. This instrument detects binding events directly through the resulting change in mass. Its presence on campus will greatly facilitate ongoing, NIH-funded basic investigations that share the fundamental long-term goal of understanding the chemical and physical principles that underlie biologically and medically relevant interactions. A wide range of systems under study here are presently hampered by the need for developing a dedicated binding assay for each one. In addition, current assays have limited dynamic range and/or prohibitive materials requirements, and yield more limited information than is available from the proposed equipment. This proposal documents how user access to the proposed instrumentation will overcome the following limitations of presently employed methods: lack of non-perturbing experimental observables that monitor binding events; prohibitively high amounts and/or concentrations of macromolecular samples; severely restricted sensitivity and dynamic range of observations; and rate-limiting throughput for multi-sample analysis. Preliminary studies are reported that demonstrate the applicability of the instrument for its intended purposes and the expertise required for its effective implementation. The instrument will also support instruction in the fundamental principles and practice of ligand-binding analysis for graduate and advanced undergraduate students.