Abstract CarH is a coenzyme B12-dependent photoreceptor involved in regulating carotenoid biosynthesis. How light-triggered cleavage of the B12 Co-C bond culminates in CarH tetramer dissociation to initiate transcription remains unclear. Here. a series of crystal structures of the CarH B12-binding domain after illumination suggest formation of unforeseen intermediate states prior to t... https://www.chiggate.com/color-charm-050-cooling-violet-supply/