Fig. 3. Reconstitution of split CarH_C induced by MeB₁₂ and CNB₁₂.

(A and D) SEC analyses of the split-CarH_C reconstitution induced by MeB₁₂ (A) or CNB₁₂ (D). “m” and “t” denote “monomer” and “tetramer,” respectively. (B and E) SDS-PAGE analyses of the split CarH_C reconstitution induced by MeB₁₂ (B) or CNB₁₂ (E). Protein samples were denatured using the 4% SDS loading dye (2×) at room temperature before the electrophoresis. (C and F) UV-vis spectra of split CarH_C in the presence of MeB₁₂ (C) or CNB₁₂. (G and H) Models of the reconstitution of split CarH_C induced by photolabile MeB₁₂ (G) and photostable CNB₁₂ (H). In the dark, CarH_CN and CarH_CC reassemble into a monomeric complex upon addition of MeB₁₂ or CNB₁₂. Photolysis of MeB₁₂ leads to the formation of a stable, monomeric complex harboring a bis-His–ligated B₁₂, while the CNB₁₂-bound complex remains unchanged on light exposure.