Crystal structure of a distal site double mutant of sperm whale myoglobin at 1.6 Å resolution

• Published in: FEBS Letters
• Main Authors: Rizzi, Menico, Bolognesi, Martino, Coda, Alessandro, Cutruzzolà, Francesca, Allocatelli, Carlo Travaglini, Brancaccio, Andrea, Brunori, Maurizio
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1993
• Subjects: Sperm whale
• Online Access: http://dx.doi.org/10.1016/0014-5793(93)81647-i; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1016%2F0014-5793%2893%2981647-I; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1016%2F0014-5793(93)81647-I; https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2893%2981647-I

The three‐dimensional structure of sperm whale myoglobin His 64 (E7)→Val,Thr 64 (E10)→Arg double mutant has been studied by X‐ray crystallography at 1.6 Å resolution, and refined to a crystallographic R ‐factor of 0.197. The Arg 67 (E10) side chain is extended in the direction of the ligand binding site, and its NH1 atom is at a distance of 3.11 Å from the NH1 atom of Arg 45 (CD3), which is also pointing towards the distal site. Both are kept in this position by hydrogen bonding and electrostatic interactions with a solvent sulfate ion, located amongst the two, on the protein surface. No liganded water molecule is present at the sixth coordination position of the Fe(III) heme.