Distal Pocket Control of Nitrite Binding in Myoglobin

Who is in charge? Nitrite linkage isomerism in the same heme protein occurs as a function of the compound preparation method. An N-bound nitrite conformation is achieved when a pre-formed iron chlorin–nitrite model compound is inserted into apoMb. In contrast, an O-bound nitrite conformation is evident when nitrite is added to the chlorin-substituted Mb. The results suggest that the Mb distal pocket is in charge of directing the ligand binding mode.