A Quantum Design superconducting susceptometer will be acquired for use by four research groups funded by NIGMS at the University of Minnesota. The instrument will be located at the Gray Freshwater Biological Institute (GFWBI) and will be used as a primary research tool in the study of the magnetization of a variety of metalloproteins. The magnetization measurements will be used in combination with EPR and, whenever possible, Mossbauer spectroscopies to characterize fully the magnetic properties of the metalloprotiens' stable redox states. The propose instrument is completely automated and makes precision magnetization in applied fields up to 5 Tesla over the broad temperature range from 1.8K to 400D. A comparable instrument located in the Physics Department on the Main Campus of the University of Minnesota is now running 24 hours a day, 365 days a year. Less than one-third of this time is available for metalloprotein studies due to the demands of other users. Rapidly growing demand is developing in the field of high temperature superconductors. A second instrument is needed at the University of Minnesota to meet the increasing demands of these two growing areas of magnetization research - metalloproteins and high temperature superconductors. The proposed (second) instrument will be located at the GFWBI in laboratory space assigned to the Principal Investigator and will be dedicated to metalloprotein studies.