Crystal structures of artificial metalloproteins: tight binding of FeIII(Schiff-Base) by mutation of Ala71 to Gly in apo-myoglobin.
Apo-myoglobin (apo-Mb) and apo-A71GMb were successfully reconstituted with FeIII(salophen) (1) (salophen = N,N'-bis(salicylidene)-1,2-phenilenediamine), Fe(III)(3,3'-Me2-salophen) (2), and FeIII(5,5'-t-Bu2-salophen) (3). The crystal structure of 2.apo-A71GMb shows the tight binding of the complex in the Mb cavity, while in wild-type apo-Mb it is highly disordered due to the steric repulsion with Ala71. Furthermore, the structure of 2.apo-A71GMb suggests a possible accommodation of a small substrate in the cavity. In fact, the cyanide association rate constant of 2.apo-A71GMb is 216-fold larger compared to that of 2.apo-Mb. These results provide us principles for the noncovalent fixation of synthetic metal cofactors at the desired positions in protein matrixes.
Ueno
Takafumi
T
Research Center for Materials Science, Nagoya University, Nagoya 464-8602, Japan.
Ohashi
Masataka
M
Kono
Masaharu
M
Kondo
Kazuyoshi
K
Suzuki
Atsuo
A
Yamane
Takashi
T
Watanabe
Yoshihito
Y
D000409:Alanine / Q000737:chemistry*; D001059:Apoproteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry*; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009154:Mutation; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics
D001059:Apoproteins; D005290:Ferric Compounds; D008667:Metalloproteins; D009211:Myoglobin; C010857:apomyoglobin; D000409:Alanine; D005998:Glycine