Structural Evolution of Photoexcited Methylcobalamin toward a CarH-like Metastable State: Evidence from Time-Resolved X-ray Absorption and X-ray Emission.
Roseanne J SensionTaylor P McClainLindsay B MichockiNicholas A MillerRoberto Alonso MoriFrederico Alves LimaFernando Ardana-LamasMykola BiednovTaewon ChungAniruddha DebYifeng JiangApril K KaneshiroDmitry KhakhulinKevin J KubarychRyan M LambJoseph H MeadowsFlorian OtteDanielle L SoffermanSanghoon SongYohei UemuraTim Brandt van DrielJames E Penner-HahnPublished in: The journal of physical chemistry. B (2024)
CarH is a protein photoreceptor that uses a form of B 12 , adenosylcobalamin (AdoCbl), to sense light via formation of a metastable excited state. Aside from AdoCbl bound to CarH, methylcobalamin (MeCbl) is the only other example─to date─of photoexcited cobalamins forming metastable excited states with lifetimes of nanoseconds or longer. The UV-visible spectra of the excited states of MeCbl and AdoCbl bound to CarH are similar. We have used transient Co K-edge X-ray absorption and X-ray emission spectroscopies in conjunction with transient absorption spectroscopy in the UV-visible region to characterize the excited states of MeCbl. These data show that the metastable excited state of MeCbl has a slightly expanded corrin ring and increased electron density on the cobalt, but only small changes in the axial bond lengths.
Keyphrases
- high resolution
- dual energy
- electron microscopy
- electron transfer
- computed tomography
- electronic health record
- cerebral ischemia
- magnetic resonance imaging
- magnetic resonance
- solid state
- gold nanoparticles
- deep learning
- small molecule
- protein protein
- quantum dots
- reduced graphene oxide
- carbon nanotubes
- metal organic framework