Data From: Shedding light on cobalamin photodegradation in the ocean

Cobalamin, vitamin B12, is an important micronutrient that has been
investigated for decades in the marine context because it is required for
phytoplankton growth. The biologically active forms (Me-B12, Ado-B12) and
the synthetic form (CN-B12) quickly convert to OH-B12 after light exposure
in various aqueous solutions, but puzzlingly have been frequently reported
to dominate dissolved cobalamin pools in the sunlit ocean. Here we
document photodegradation timescales for these cobalamin forms in natural
seawater using targeted mass spectrometry, providing quantitative evidence
that OH-B12 is expected to be the dominant dissolved form in irradiated
seawater. Then, through high resolution mass spectrometry, we identify
four photodegradation products of OH-B12 which represent potential
building blocks microbes could salvage and remodel to satisfy cellular
cobalamin requirements. Taken together, these results clarify the impact
of light on marine cobalamin dynamics, laying a foundation for a more
quantitative understanding of the role of cobalamin in microbial
communities and biogeochemical cycles.