1eb7
From Proteopedia
| Line 5: | Line 5: | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Cytochrome c peroxidase from Pseudomonas aeruginosa (PsCCP), represents a new class of peroxidases which work without the need to, create a semi-stable free radical for catalysis. The enzyme is located in, the bacterial periplasm where its likely function is to provide protection, against toxic peroxides. The soluble 323-residue single polypeptide chain, contains two covalent c-type haems with very different properties: one of, them is a low-potential (-330 mV) centre where hydrogen peroxide is, reduced (the peroxidatic site); the other is a high-potential (+320 mV), centre which feeds electrons to the peroxidatic site from soluble, electron-shuttle proteins such as cytochrome c and azurin. RESULTS: The, crystal structure of the oxidized form of PsCCP has been determined to ... | + | BACKGROUND: Cytochrome c peroxidase from Pseudomonas aeruginosa (PsCCP), represents a new class of peroxidases which work without the need to, create a semi-stable free radical for catalysis. The enzyme is located in, the bacterial periplasm where its likely function is to provide protection, against toxic peroxides. The soluble 323-residue single polypeptide chain, contains two covalent c-type haems with very different properties: one of, them is a low-potential (-330 mV) centre where hydrogen peroxide is, reduced (the peroxidatic site); the other is a high-potential (+320 mV), centre which feeds electrons to the peroxidatic site from soluble, electron-shuttle proteins such as cytochrome c and azurin. RESULTS: The, crystal structure of the oxidized form of PsCCP has been determined to 2.4, A resolution by multiple isomorphous replacement, and refined to an, R-factor of 19.2%. PsCCP is organized into two domains, both of them, containing a covalent c-haem in a structure reminiscent of class 1, cytochromes c. The domains are related by a quasi-twofold axis. The domain, interface holds a newly discovered calcium-binding site with an unusual, set of ligands. CONCLUSIONS: The likely function of the calcium site is to, maintain the structural integrity of the enzyme and/or to modulate, electron transfer between the two haem domains. The low-potential haem has, two histidine axial ligands (His55 and His71) and the high-potential haem, is ligated by His201 and Met275. There are no polar residues at the, peroxidatic site in the inactive oxidized enzyme. The structure suggests, that, in the half-reduced functional form of the enzyme, the low-potential, haem has to shed His71 in order to make the enzyme catalytically, competent. This process is likely to trigger a reorganization of the, active site, and may introduce a new residues into the haem pocket. |
==About this Structure== | ==About this Structure== | ||
| - | 1EB7 is a | + | 1EB7 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa] with CA and HEC as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Structure known Active Sites: 401, 402 and 403. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1EB7 OCA]. |
==Reference== | ==Reference== | ||
| Line 23: | Line 23: | ||
[[Category: peroxidase]] | [[Category: peroxidase]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 13:09:23 2007'' |
Revision as of 11:04, 5 November 2007
|
CRYSTAL STRUCTURE OF THE DI-HAEM CYTOCHROME C PEROXIDASE FROM PSEUDOMONAS AERUGINOSA
Overview
BACKGROUND: Cytochrome c peroxidase from Pseudomonas aeruginosa (PsCCP), represents a new class of peroxidases which work without the need to, create a semi-stable free radical for catalysis. The enzyme is located in, the bacterial periplasm where its likely function is to provide protection, against toxic peroxides. The soluble 323-residue single polypeptide chain, contains two covalent c-type haems with very different properties: one of, them is a low-potential (-330 mV) centre where hydrogen peroxide is, reduced (the peroxidatic site); the other is a high-potential (+320 mV), centre which feeds electrons to the peroxidatic site from soluble, electron-shuttle proteins such as cytochrome c and azurin. RESULTS: The, crystal structure of the oxidized form of PsCCP has been determined to 2.4, A resolution by multiple isomorphous replacement, and refined to an, R-factor of 19.2%. PsCCP is organized into two domains, both of them, containing a covalent c-haem in a structure reminiscent of class 1, cytochromes c. The domains are related by a quasi-twofold axis. The domain, interface holds a newly discovered calcium-binding site with an unusual, set of ligands. CONCLUSIONS: The likely function of the calcium site is to, maintain the structural integrity of the enzyme and/or to modulate, electron transfer between the two haem domains. The low-potential haem has, two histidine axial ligands (His55 and His71) and the high-potential haem, is ligated by His201 and Met275. There are no polar residues at the, peroxidatic site in the inactive oxidized enzyme. The structure suggests, that, in the half-reduced functional form of the enzyme, the low-potential, haem has to shed His71 in order to make the enzyme catalytically, competent. This process is likely to trigger a reorganization of the, active site, and may introduce a new residues into the haem pocket.
About this Structure
1EB7 is a Single protein structure of sequence from Pseudomonas aeruginosa with CA and HEC as ligands. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Structure known Active Sites: 401, 402 and 403. Full crystallographic information is available from OCA.
Reference
Crystal structure of the di-haem cytochrome c peroxidase from Pseudomonas aeruginosa., Fulop V, Ridout CJ, Greenwood C, Hajdu J, Structure. 1995 Nov 15;3(11):1225-33. PMID:8591033
Page seeded by OCA on Mon Nov 5 13:09:23 2007
