4atj
From Proteopedia
(New page: 200px<br /><applet load="4atj" size="450" color="white" frame="true" align="right" spinBox="true" caption="4atj, resolution 2.50Å" /> '''DISTAL HEME POCKET M...) |
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| - | [[Image:4atj.gif|left|200px]]<br /><applet load="4atj" size=" | + | [[Image:4atj.gif|left|200px]]<br /><applet load="4atj" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="4atj, resolution 2.50Å" /> | caption="4atj, resolution 2.50Å" /> | ||
'''DISTAL HEME POCKET MUTANT (H42E) OF RECOMBINANT HORSERADISH PEROXIDASE IN COMPLEX WITH BENZHYDROXAMIC ACID'''<br /> | '''DISTAL HEME POCKET MUTANT (H42E) OF RECOMBINANT HORSERADISH PEROXIDASE IN COMPLEX WITH BENZHYDROXAMIC ACID'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structures of horseradish peroxidase C (HRPC) active-site | + | The crystal structures of horseradish peroxidase C (HRPC) active-site mutants H42E and R38S/H42E co-crystallized with benzhydroxamic acid (BHA) and ferulic acid (FA), respectively, have been solved. The 2.5 A crystal structure of the H42E-BHA complex reveals that the side-chain O atoms of Glu42 occupy positions that are very similar to the positions of the two side-chain N atoms of the distal histidine in the wild-type HRPC-BHA structure. The mutation disturbs the hydrogen-bonding network extending from residue 42 to the distal calcium ion and results in the absence of the water molecule that is usually ligated to this ion in plant peroxidases. Consequently, the distal calcium ion is six- rather than seven-coordinated. In the 2.0 A R38S/H42E structure the position of Glu42 is different and no FA is observed in the distal haem pocket. This is a consequence of the absence of the Arg38 side chain, which limits the flexibility of the Glu42 side chain and modulates its acidity, making it unsuitable as a general acid-base catalyst in the reaction cycle. The water ligated to the distal calcium ion is present, showing that the wild-type distal hydrogen-bonding network is preserved. These results show why a glutamic acid residue can substitute for the conserved distal histidine in HRPC and that Arg38 plays a significant role in controlling the positioning and ionization state of the residue at position 42. Furthermore, these structures indicate that changes in the distal cavity are conveyed through the distal hydrogen-bonding network to the distal calcium site. |
==About this Structure== | ==About this Structure== | ||
| - | 4ATJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Armoracia_rusticana Armoracia rusticana] with CA, HEM and BHO as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Peroxidase Peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.7 1.11.1.7] Full crystallographic information is available from [http:// | + | 4ATJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Armoracia_rusticana Armoracia rusticana] with <scene name='pdbligand=CA:'>CA</scene>, <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=BHO:'>BHO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Peroxidase Peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.7 1.11.1.7] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4ATJ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Jennings, S.]] | [[Category: Jennings, S.]] | ||
[[Category: Meno, K.]] | [[Category: Meno, K.]] | ||
| - | [[Category: Smith, A | + | [[Category: Smith, A T.]] |
[[Category: BHO]] | [[Category: BHO]] | ||
[[Category: CA]] | [[Category: CA]] | ||
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[[Category: peroxidase]] | [[Category: peroxidase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:12:45 2008'' |
Revision as of 17:12, 21 February 2008
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DISTAL HEME POCKET MUTANT (H42E) OF RECOMBINANT HORSERADISH PEROXIDASE IN COMPLEX WITH BENZHYDROXAMIC ACID
Overview
The crystal structures of horseradish peroxidase C (HRPC) active-site mutants H42E and R38S/H42E co-crystallized with benzhydroxamic acid (BHA) and ferulic acid (FA), respectively, have been solved. The 2.5 A crystal structure of the H42E-BHA complex reveals that the side-chain O atoms of Glu42 occupy positions that are very similar to the positions of the two side-chain N atoms of the distal histidine in the wild-type HRPC-BHA structure. The mutation disturbs the hydrogen-bonding network extending from residue 42 to the distal calcium ion and results in the absence of the water molecule that is usually ligated to this ion in plant peroxidases. Consequently, the distal calcium ion is six- rather than seven-coordinated. In the 2.0 A R38S/H42E structure the position of Glu42 is different and no FA is observed in the distal haem pocket. This is a consequence of the absence of the Arg38 side chain, which limits the flexibility of the Glu42 side chain and modulates its acidity, making it unsuitable as a general acid-base catalyst in the reaction cycle. The water ligated to the distal calcium ion is present, showing that the wild-type distal hydrogen-bonding network is preserved. These results show why a glutamic acid residue can substitute for the conserved distal histidine in HRPC and that Arg38 plays a significant role in controlling the positioning and ionization state of the residue at position 42. Furthermore, these structures indicate that changes in the distal cavity are conveyed through the distal hydrogen-bonding network to the distal calcium site.
About this Structure
4ATJ is a Single protein structure of sequence from Armoracia rusticana with , and as ligands. Active as Peroxidase, with EC number 1.11.1.7 Full crystallographic information is available from OCA.
Reference
Structural analysis of the two horseradish peroxidase catalytic residue variants H42E and R38S/H42E: implications for the catalytic cycle., Meno K, Jennings S, Smith AT, Henriksen A, Gajhede M, Acta Crystallogr D Biol Crystallogr. 2002 Oct;58(Pt 10 Pt 2):1803-12. Epub, 2002 Sep 28. PMID:12351824
Page seeded by OCA on Thu Feb 21 19:12:45 2008
Categories: Armoracia rusticana | Peroxidase | Single protein | Gajhede, M. | Henriksen, A. | Jennings, S. | Meno, K. | Smith, A T. | BHO | CA | HEM | Heme enzyme | Mutant | Oxidoreductase
