BIOINORGANIC APPLICATIONS OF X-RAY MULTIPLETS - THE IMPACT OF THOLE,THEO WORK

Prior to the work of Thee Thole and his collaborators, the vast majori ty of biological X-ray spectroscopy involved either EXAFS or hard X-ra y XANES spectroscopy. Thee Thole's ligand field multiplet theory revea led the rich information content of transition metal L-edges, and it h elped prompt the first measurements on metalloproteins. His contributi ons to XMCD also prompted the first low-temperature/high-field experim ents on paramagnetic centers in proteins, This paper describes some re cent work in biological soft X-ray spectroscopy that was stimulated by Thole's findings, Representative Ni protein absorption spectra are sh own, illustrating detection of Ni(I), NL(III), and high-and low-spin N i(II) in Ni hydrogenase and CO dehydrogenase, New XMCD spectra for Cu in plastocyanin and Fe in a 2Fe ferredoxin are presented. The exciting prospects for soft X-ray absorption and XMCD of metalloproteins are s ummarized. (C) 1997 Elsevier Science B.V.