The haem distal site of <i>Ma</i>Pgb*(III)-cyanide Trp(60)B9Ala and Tyr(61)B10Ala mutants.

<p>Residues lining the haem distal pocket are indicated and shown in stick representation (grey). Superimposition of <i>Ma</i>Pgb*(III)-cyanide (yellow) onto (<b>A</b>) the <i>Ma</i>Pgb*(III)-cyanide Trp(60)B9Ala mutant, and (<b>B</b>) the <i>Ma</i>Pgb*(III)-cyanide Tyr(61)B10Ala mutant. The proximal His(120)F8 residue is also shown. H-bonds to the haem-Fe(III)-bound cyanide are indicated by dashed lines. The mutated residues are indicated in underlined bold characters. Both panels are shown from side and top views.