Figure 2.

Views of the active site of catalytically inactive mutants of B. subtilis levansucrase. Difference electron density maps were calculated with Fourier coefficients (F_o,mutant - F_o,wild-type) and model phases derived from the wild-type enzyme structure (1OYG, [11]). The maps (2.1 Å resolution) are contoured at 5σ (panels A-C) or 4σ (panel D), with positive and negative density in blue and red, respectively. The stick models are colour-coded by carbon atoms as follows: wild type enzyme (green), D86A (magenta – panel A), D247A (yellow – panel B), E342A (grey – panel C) and raffinose-bound E342A (pale red – panel D).