2EKT
Crystal structure of myoglobin reconstituted with 6-methyl-6-depropionatehemin
Summary for 2EKT
| Entry DOI | 10.2210/pdb2ekt/pdb |
| Related | 2EKU |
| Descriptor | Myoglobin, SULFATE ION, 6-METHY-6-DEPROPIONATEHEMIN, ... (4 entities in total) |
| Functional Keywords | globin fold, oxygen storage-transport complex, oxygen storage/transport |
| Biological source | Physeter catodon (sperm whale) |
| Total number of polymer chains | 1 |
| Total formula weight | 18177.65 |
| Authors | Harada, K.,Makino, M.,Sugimoto, H.,Hirota, S.,Matsuo, T.,Shiro, Y.,Hisaeda, Y.,Hayashi, T. (deposition date: 2007-03-25, release date: 2007-08-14, Last modification date: 2023-10-25) |
| Primary citation | Harada, K.,Makino, M.,Sugimoto, H.,Hirota, S.,Matsuo, T.,Shiro, Y.,Hisaeda, Y.,Hayashi, T. Structure and ligand binding properties of myoglobins reconstituted with monodepropionated heme: functional role of each heme propionate side chain Biochemistry, 46:9406-9416, 2007 Cited by PubMed Abstract: 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. PubMed: 17636874DOI: 10.1021/bi7007068 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.1 Å) |
Structure validation
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