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| {{STRUCTURE_2ekt| PDB=2ekt | SCENE= }} | | {{STRUCTURE_2ekt| PDB=2ekt | SCENE= }} |
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| '''Crystal structure of myoglobin reconstituted with 6-methyl-6-depropionatehemin'''
| | ===Crystal structure of myoglobin reconstituted with 6-methyl-6-depropionatehemin=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17636874}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17636874 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17636874}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Globin fold]] | | [[Category: Globin fold]] |
| [[Category: Oxygen storage/transport complex]] | | [[Category: Oxygen storage/transport complex]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 02:41:51 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 05:38:45 2008'' |
