COMPUTER APPLICATIONS IN QUANTITATIVE EPR SPECTROSCOPY OF METALLOPROTEINS (FERRITIN, APOFERRITIN, IRON)

This dissertation examines the use of computers in quantitative EPR spectroscopy. The computers used ranged from hand held calculators to large main frame systems. Applications discussed are protein assay calculations, an EPR minicomputer interface and software system and the modification of an existing EPR simulation program to include corrections for strains in the g and A tensors. The modification permits more accurate linewidth simulation for lines with large M(,I) values. The computer interface and software allows for the collection of EPR spectra, which can then be stored, scaled, added, subtracted (for comparison) and double integrated. The program enhances weak signals by signal averaging. Double integration was used to assist in the study of early iron binding in horse spleen apoferritin. Iron(II) was added to apoferritin followed by oxidation by a variety of methods. In all cases an iron(III) EPR signal was observed at g\u27 = 4.3 which was attributed to mononuclear Fe(III) bound to the protein; this signal increased until 0.5 equivalent per subunit of added iron. In another experiment increasing amounts of Tb(III) were added to apoferritin solutions. Subsequent addition of 0.5 equivalent of iron(II) per subunit resulted in an Fe(III) signal that decreased as a function of added Tb(III). It was also found that ultracentrifugation of commercial ferritin yields a light, low iron content, fraction which showed a majority of the iron signal intensity relative to the heavy, iron rich, fraction. These results suggest that iron core starts to form at an initial binding site that lies between two adjacent subunits resulting in a 0.5 equivalent of binding site per subunit and that this site also serves as the nucleus of core formation within the ferritin molecule. As the core grows beyond 0.5 equivalents per subunit more of the mononuclear sites are converted into growing core. At 0.5 equivalents per subunit double integration shows that only 20% of the added iron is EPR active suggesting a majority of the added iron is present as polymeric iron (core) species

1991 OURE report, including the 1st Annual UMR Undergraduate Research Symposium -- Entire Proceedings

The Opportunities for Undergraduate Research Experiences program began in 1990. The aims were to enrich the learning process and make it more active, encourage interaction between students and faculty members, raise the level of research on the campus, help recruit superior students to the graduate program, and support the notion that teaching and research are compatible and mutually reinforcing. Chancellor Jischke made available an annual budget of $50,000 to support the program. As the papers herein attest, the OURE program is achieving its goals — UMR graduates have performed research on an enormous variety of topics, have worked closely with faculty members, and have experienced deeply both the pleasures and frustrations of research. Several of the undergraduates whose papers are included are now graduate students at UMR or elsewhere. Others, who have not yet graduated, are eager to submit proposals to the next OURE round. I am sure all involved join me in expressing gratitude to Chancellor Jischke for inaugurating the program. The first section of this volume is made up of papers presented at the first annual UMR Undergraduate Research Symposium, held in April 1991. Joining the UMR undergraduates in the Symposium were students from other colleges and universities who had participated in an NSF- sponsored summer program of research on parallel processing conducted by the UMR Computer Science Department

The Twenty-Fifth Lunar and Planetary Science Conference. Part 3: P-Z

Various papers on lunar and planetary science are presented, covering such topics as: impact craters, tektites, lunar geology, lava flow, geodynamics, chondrites, planetary geology, planetary surfaces, volcanology, tectonics, topography, regolith, metamorphic rock, geomorphology, lunar soil, geochemistry, petrology, cometary collisions, geochronology, weathering, and meteoritic composition