Stereo view of the docking site of the photolyzed CO* in Mb-YQR at 20 K. The site is defined as being formed by the residues having at least one atom at 5 Å or less from one of the two atoms of CO* and include: Gly(B6)25, Ile(B9)28, Tyr(B10)29, Gly(E8)65, Val(E11)68, Leu(E12)69, and Ile(G8)107. The distance of the CO* from the heme Fe is shown in Å.