Infrared spectroscopic evidence of hydrogen bonding between carbon monoxide and protein in carbonylhorseradish peroxidase C

Carbonylhorseradish peroxidase isoenzyme C 2 (EC 1.11.1.7) exhibits two bands in the infrared spectrum attributable to the ligand CO at 1933.5 and 1905 cm −1 . Replacement of H 2 O by D 2 O results in shifts to both bands to new positions at 1932.5 and 1902.5 cm −1 . The results indicate strong hydrogen bonding to the terminal oxygen of CO, of strength comparable to that recently observed for oxyhemoglobin and oxymyoglobin.