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

[摘要]

The three-dimensional structure of sperm whale myoglobin His⁶⁴(E7)→Val,Thr⁶⁴(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 Arg⁶⁷(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 Arg⁴⁵(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.

[学科分类] 生物化学/生物物理

[关键词] Protein engineering;Myoglobin mutant;Ligand binding;NMR;nuclear magnetic resonance;V mutant;HiS64(E7)→Val sperm whale myoglobin single mutant;VR mutant;HiS64(E7)→Val;Thr67(E10)→Arg sperm whale myoglobin double mutant;Mb;myoglobin;rms;root mean square;Rsym. merging R-factor between symmetry related reflections:where Ihis the observed intensity of the j-th measurement of reflection h;and is its mean value. Amino acid residues have been identified by their three-letter codes;sequence number and topological position [1] within the conventional globin fold