1bsw
From Proteopedia
(New page: 200px<br /><applet load="1bsw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bsw, resolution 1.95Å" /> '''ACUTOLYSIN A FROM SN...) |
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| - | [[Image:1bsw.gif|left|200px]]<br /><applet load="1bsw" size=" | + | [[Image:1bsw.gif|left|200px]]<br /><applet load="1bsw" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1bsw, resolution 1.95Å" /> | caption="1bsw, resolution 1.95Å" /> | ||
'''ACUTOLYSIN A FROM SNAKE VENOM OF AGKISTRODON ACUTUS AT PH 7.5'''<br /> | '''ACUTOLYSIN A FROM SNAKE VENOM OF AGKISTRODON ACUTUS AT PH 7.5'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Acutolysin A alias AaHI, a 22 kDa hemorrhagic toxin isolated from the | + | Acutolysin A alias AaHI, a 22 kDa hemorrhagic toxin isolated from the snake venom of Agkistrodon acutus, is a member of the adamalysin subfamily of the metzincin family and is a snake venom zinc metalloproteinase possessing only one catalytic domain. Acutolysin A was found to have a high-activity and a low-activity under weakly alkaline and acidic conditions, respectively. With the adamalysin II structure as the initial trial-and-error model, the crystal structures were solved to the final crystallographic R-factors of 0. 168 and 0.171, against the diffraction data of crystals grown under pH 5.0 and pH 7.5 conditions to 1.9 A and 1.95 A resolution, respectively. One zinc ion, binding in the active-site, one structural calcium ion and some water molecules were localized in both of the structures. The catalytic zinc ion is coordinated in a tetrahedral manner with one catalytic water molecule anchoring to an intermediate glutamic acid residue (Glu143) and three imidazole Nepsilon2 atoms of His142, His146 and His152 in the highly conserved sequence H142E143XXH146XXGXXH152. There are two new disulfide bridges (Cys157-Cys181 and Cys159-Cys164) in acutolysin A in addition to the highly conserved disulfide bridge Cys117-Cys197. The calcium ion occurs on the molecular surface. The superposition showed that there was no significant conformational changes between the two structures except for a few slight changes of some flexible residue side-chains on the molecular surface, terminal residues and the active-site cleft. The average contact distance between the catalytic water molecule and oxygen atoms of the Glu143 carboxylate group in the weakly alkaline structure was also found to be closer than that in the weakly acidic structure. By comparing the available structural information of the members of the adamalysin subfamily, it seems that, when lowering the pH value, the polarization capability of the Glu143 carboxylate group to the catalytic water molecule become weaker, which might be the structural reason why the snake venom metalloproteinases are inactive or have a low activity under acidic conditions. |
==About this Structure== | ==About this Structure== | ||
| - | 1BSW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Deinagkistrodon_acutus Deinagkistrodon acutus] with ZN and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1BSW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Deinagkistrodon_acutus Deinagkistrodon acutus] with <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BSW OCA]. |
==Reference== | ==Reference== | ||
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[[Category: snake venom]] | [[Category: snake venom]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:58:48 2008'' |
Revision as of 09:58, 21 February 2008
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ACUTOLYSIN A FROM SNAKE VENOM OF AGKISTRODON ACUTUS AT PH 7.5
Overview
Acutolysin A alias AaHI, a 22 kDa hemorrhagic toxin isolated from the snake venom of Agkistrodon acutus, is a member of the adamalysin subfamily of the metzincin family and is a snake venom zinc metalloproteinase possessing only one catalytic domain. Acutolysin A was found to have a high-activity and a low-activity under weakly alkaline and acidic conditions, respectively. With the adamalysin II structure as the initial trial-and-error model, the crystal structures were solved to the final crystallographic R-factors of 0. 168 and 0.171, against the diffraction data of crystals grown under pH 5.0 and pH 7.5 conditions to 1.9 A and 1.95 A resolution, respectively. One zinc ion, binding in the active-site, one structural calcium ion and some water molecules were localized in both of the structures. The catalytic zinc ion is coordinated in a tetrahedral manner with one catalytic water molecule anchoring to an intermediate glutamic acid residue (Glu143) and three imidazole Nepsilon2 atoms of His142, His146 and His152 in the highly conserved sequence H142E143XXH146XXGXXH152. There are two new disulfide bridges (Cys157-Cys181 and Cys159-Cys164) in acutolysin A in addition to the highly conserved disulfide bridge Cys117-Cys197. The calcium ion occurs on the molecular surface. The superposition showed that there was no significant conformational changes between the two structures except for a few slight changes of some flexible residue side-chains on the molecular surface, terminal residues and the active-site cleft. The average contact distance between the catalytic water molecule and oxygen atoms of the Glu143 carboxylate group in the weakly alkaline structure was also found to be closer than that in the weakly acidic structure. By comparing the available structural information of the members of the adamalysin subfamily, it seems that, when lowering the pH value, the polarization capability of the Glu143 carboxylate group to the catalytic water molecule become weaker, which might be the structural reason why the snake venom metalloproteinases are inactive or have a low activity under acidic conditions.
About this Structure
1BSW is a Single protein structure of sequence from Deinagkistrodon acutus with and as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structures of acutolysin A, a three-disulfide hemorrhagic zinc metalloproteinase from the snake venom of Agkistrodon acutus., Gong W, Zhu X, Liu S, Teng M, Niu L, J Mol Biol. 1998 Oct 30;283(3):657-68. PMID:9784374
Page seeded by OCA on Thu Feb 21 11:58:48 2008
Categories: Deinagkistrodon acutus | Single protein | Gong, W. | Liu, S. | Niu, L. | Teng, M. | Zhu, X. | CA | ZN | Metalloproteinase | Mmp | Snake venom
