... G.C., Katakura, K., Tomita, T., Zhang, X., Sun, D., Sato,M., Sasahara, M., Kayama, T., Ikeda-Saito, M. & Yoshida, T.(2000) Histidine 20, the crucial proximal axial heme ligand of bacterial ... Fig. 7, panel A. Addition of ascorbate to the heme–Syn HO-1 complexcommences the reaction, which is monitored by the steadydecrease of the Soret and 498 nm bands and the shift of the band at 630 ... proximalligand, presumably histidine 17 and the obtained EPRparameters are discriminated from those of the rat hemeoxygenase-1 complex. The spectroscopic characters as wellas the catabolic activities...