Relative positions of Tyr145 and Asp145 with respect to the heme.

<p>Dashed lines correspond to the temporary distances in Å between the heme oxygen and the corresponding hydrogen atoms which undergo time variations during the simulation. Occasionally, Tyr145 forms a hydrogen bond to the heme when internal motion of the protein brings Tyr145 closer to the heme. There is no hydrogen bond formed between Asp145 and heme as they are too far apart from each other.