Figure 4: The enzymatic reaction in the crystalline state.

(a) The BV reduction could proceed in the crystal by adding NADPH. Right, 10 min after the reaction. The bluish-green colour in the crystal (left) is derived from the bound BV. The yellow–green colour in the crystal (right) is probably derived from the mixture of BV and BR. Scale bar, 20 μm (b) The colours of the pigments in solution, provided as a reference: BV (left); mixture of BV and BR (middle) and BR (right). Final concentrations of all pigments were adjusted to 0.5 mM.