2ekt
|
Crystal structure of myoglobin reconstituted with 6-methyl-6-depropionatehemin
OverviewOverview
Two heme propionate side chains, which are attached at the 6 and 7, positions of the heme framework, are linked with Arg45 and Ser92, respectively, in sperm whale myoglobin. To evaluate the role of each, propionate, two kinds of one-legged hemins, 6-depropionated and, 7-depropionated protohemins, were prepared and inserted into the, apomyoglobin to yield two reconstituted proteins. Structural data of the, reconstituted myoglobins were obtained via an X-ray crystallographic, analysis at a resolution of 1.1-1.4 A and resonance Raman spectroscopy. It, was found that the lack of the 6-propionate reduces the number of hydrogen, bonds in the distal site and clearly changes the position of the Arg45, residue with the disrupting Arg45-Asp60 interaction. In contrast, the, removal of the 7-propionate does not cause a significant structural change, in the residues of the distal and proximal sites. However, the resonance, Raman studies suggested that the coordination bond strength of the, His93-Fe bond for the protein with the 7-depropionated protoheme slightly, increases compared to that for the protein with the native heme. The O2, and CO ligand binding studies for the reconstituted proteins with the, one-legged hemes provide an important insight into the functional role of, each propionate. The lack of the 6-propionate accelerates the O2, dissociation by ca. 3-fold compared to those of the other reconstituted, and native proteins. The lack of the 7-propionate enhances the CO affinity, by 2-fold compared to that of the protein with the native heme. These, results indicate that the 6-propionate clearly contributes to the, stabilization of the bound O2, whereas the 7-propionate plays an important, role in the regulation of the Fe-His bond.
About this StructureAbout this Structure
2EKT is a Single protein structure of sequence from Physeter catodon with SO4 and 6HE as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structure and ligand binding properties of myoglobins reconstituted with monodepropionated heme: functional role of each heme propionate side chain., Harada K, Makino M, Sugimoto H, Hirota S, Matsuo T, Shiro Y, Hisaeda Y, Hayashi T, Biochemistry. 2007 Aug 21;46(33):9406-16. Epub 2007 Jul 18. PMID:17636874
Page seeded by OCA on Wed Nov 21 10:04:55 2007