1m20: Difference between revisions
New page: left|200px<br /><applet load="1m20" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m20, resolution 1.80Å" /> '''Crystal Structure of... |
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[[Image:1m20.gif|left|200px]]<br /><applet load="1m20" size=" | [[Image:1m20.gif|left|200px]]<br /><applet load="1m20" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1m20, resolution 1.80Å" /> | caption="1m20, resolution 1.80Å" /> | ||
'''Crystal Structure of F35Y Mutant of Trypsin-solubilized Fragment of Cytochrome b5'''<br /> | '''Crystal Structure of F35Y Mutant of Trypsin-solubilized Fragment of Cytochrome b5'''<br /> | ||
==Overview== | ==Overview== | ||
Conserved phenylalanine 35 is one of the hydrophobic patch residues on the | Conserved phenylalanine 35 is one of the hydrophobic patch residues on the surface of cytochrome b5 (cyt b5). This patch is partially exposed on the surface of cyt b5 while its buried face is in direct van der Waals' contact with heme b. Residues Phe35 and Phe/Tyr74 also form an aromatic channel with His39, which is one of the axial ligands of heme b. By site-directed mutagenesis we have produced three mutants of cyt b5: Phe35-->Tyr, Phe35-->Leu, and Phe35-->His. We found that of these three mutants, the Phe35-->Tyr mutant displays abnormal properties. The redox potential of the Phe35-->Tyr mutant is 66 mV more negative than that of the wild-type cyt b5 and the oxidized Phe35-->Tyr mutant is more stable towards thermal and chemical denaturation than wild-type cyt b5. In this study we studied the most interesting mutant, Phe35-->Tyr, by X-ray crystallography, thermal denaturation, CD and kinetic studies of heme dissociation to explore the origin of its unusual behaviors. Analysis of crystal structure of the Phe35-->Tyr mutant shows that the overall structure of the mutant is basically the same as that of the wild-type protein. However, the introduction of a hydroxyl group in the heme pocket, and the increased van der Waals' and electrostatic interactions between the side chain of Tyr35 and the heme probably result in enhancement of stability of the Phe35-->Tyr mutant. The kinetic difference of the heme trapped by the heme pocket also supports this conclusion. The detailed conformational changes of the proteins in response to heat have been studied by CD for the first time, revealing the existence of the folding intermediate. | ||
==About this Structure== | ==About this Structure== | ||
1M20 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1M20 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M20 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Bos taurus]] | [[Category: Bos taurus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Huang, Z | [[Category: Huang, Z X.]] | ||
[[Category: Sun, B | [[Category: Sun, B Y.]] | ||
[[Category: Wang, Y | [[Category: Wang, Y H.]] | ||
[[Category: Wu, J.]] | [[Category: Wu, J.]] | ||
[[Category: Xia, Z | [[Category: Xia, Z X.]] | ||
[[Category: Yao, P.]] | [[Category: Yao, P.]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
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[[Category: trypsin-cleaved fragment]] | [[Category: trypsin-cleaved fragment]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:50:38 2008'' | ||
