ic500873y_si_001.pdf (7.3 MB)
Pyranopterin Dithiolene Distortions Relevant to Electron Transfer in Xanthine Oxidase/Dehydrogenase
journal contribution
posted on 2015-12-17, 03:22 authored by Chao Dong, Jing Yang, Silke Leimkühler, Martin L. KirkThe reducing substrates 4-thiolumazine
and 2,4-dithiolumazine have
been used to form MoIV-product complexes with xanthine
oxidase (XO) and xanthine dehydrogenase. These MoIV-product
complexes display an intense metal-to-ligand charge-transfer (MLCT)
band in the near-infrared region of the spectrum. Optical pumping
into this MLCT band yields resonance Raman spectra of the Mo site
that are devoid of contributions from the highly absorbing FAD and
2Fe2S clusters in the protein. The resonance Raman spectra reveal
in-plane bending modes of the bound product and low-frequency molybdenum
dithiolene and pyranopterin dithiolene vibrational modes. This work
provides keen insight into the role of the pyranopterin dithiolene
in electron-transfer reactivity.