Abstract
Electron transfer crucial to bioenergetics is ubiquitously present in biological systems
but most of them escape from direct observations. By using tryptophan and its
derivatives with 1-CH3, 2-CH3, 5-CH3 and 5-OH substitutions as model molecules,
we have unambiguously demonstrated successive two-electron transfer to tryptophan
as well as electronic and vibrational excited molecular dissociation with mass
spectrometry. The ultra-short time delay between two electrons down to
sub-attosecond over a distance less than 10 Å was found to cause the strong coupling
of electronic and vibrational excitations that was validated by the observation of
radical-radical coupling. Intramolecular H migrations along with two-electron
transfer was demonstrated with H/D exchange and 13C stable isotope labeling. This
proposed technique allows us to observe the ultrafast electron transfer from
tryptophan to the heme group in myoglobin proteins. It bridges electron transfer to
energy transfer that has been revealed in FRET alone. FeII (porph•‐) and FeI
(porph•‐)
resulting from one- and two-electron transfer, respectively, have been unambiguously
identified
Supplementary materials
Title
Supporting Information-Zhong-revised
Description
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