1ch9: Difference between revisions

Revision as of 12:44, 2 May 2008

RECOMBINANT SPERM WHALE MYOGLOBIN H97Q MUTANT (MET)

OverviewOverview

The ability of myoglobin to bind oxygen reversibly depends critically on retention of the heme prosthetic group. Globin side chains at the Leu(89)(F4), His(97)(FG3), Ile(99)(FG5), and Leu(104)(G5) positions on the proximal side of the heme pocket strongly influence heme affinity. The roles of these amino acids in preventing heme loss have been examined by determining high resolution structures of 14 different mutants at these positions using x-ray crystallography. Leu(89) and His(97) are important surface amino acids that interact either sterically or electrostatically with the edges of the porphyrin ring. Ile(99) and Leu(104) are located in the interior region of the proximal pocket beneath ring C of the heme prosthetic group. The apolar amino acids Leu(89), Ile(99), and Leu(104) "waterproof" the heme pocket by forming a barrier to solvent penetration, minimizing the size of the proximal cavity, and maintaining a hydrophobic environment. Substitutions with smaller or polar side chains at these positions result in exposure of the heme to solvent, the appearance of crystallographically defined water molecules in or near the proximal pocket, and large increases in the rate of hemin loss. Thus, the naturally occurring amino acid side chains at these positions serve to prevent hydration of the His(93)-Fe(III) bond and are highly conserved in all known myoglobins and hemoglobins.

About this StructureAbout this Structure

1CH9 is a Single protein structure of sequence from Physeter catodon. Full crystallographic information is available from OCA.

ReferenceReference

Waterproofing the heme pocket. Role of proximal amino acid side chains in preventing hemin loss from myoglobin., Liong EC, Dou Y, Scott EE, Olson JS, Phillips GN Jr, J Biol Chem. 2001 Mar 23;276(12):9093-100. Epub 2000 Nov 17. PMID:11084036 Page seeded by OCA on Fri May 2 12:44:02 2008

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OCA

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 [[Image:1ch9.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 1ch9 |SIZE=350|CAPTION= <scene name='initialview01'>1ch9</scene>, resolution 1.80&Aring;
+The line below this paragraph, containing "STRUCTURE_1ch9", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1ch9|  PDB=1ch9  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ch9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ch9 OCA], [http://www.ebi.ac.uk/pdbsum/1ch9 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1ch9 RCSB]</span>
-}}
 '''RECOMBINANT SPERM WHALE MYOGLOBIN H97Q MUTANT (MET)'''
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 [[Category: Jr., G N.Phillips.]]
 [[Category: Liong, E C.]]
-[[Category: heme]]
+[[Category: Heme]]
-[[Category: muscle protein]]
+[[Category: Muscle protein]]
-[[Category: oxygen transport]]
+[[Category: Oxygen transport]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 12:44:02 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 19:21:43 2008''