The structure of cobalamin is shown in a stereoscopic view in the figure. It contains a central Co ion with 4-fold coordination with a corrin ring. It has axial coordination with DMB at the lower axial position one of 4 at the upper axial position. It is a cofactor for ethanolamine ammonida lyase (EAL), a Class II enzyme that catalyzes the rearrangement of 1,2 aminoalcohols. We have measured the 3D spectrum of cobalamin using Triply Resonant Sum Frequency spectroscopy where three tunable picosecond laser pulses excite two vibrational states and the electronic state. Spectra are acquired by scanning the frequencies of all three lasers and measuring the output intensity. The spectra contain cross-peaks involving short and long axis vibrational modes and coupling to vibronic states of the excited electronic states.

Multiresonant coherent multidimensional spectroscopy of cobalamin

253rd National Meeting (2017)

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