This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
2ctx
From Proteopedia
(New page: 200px<br /><applet load="2ctx" size="450" color="white" frame="true" align="right" spinBox="true" caption="2ctx, resolution 2.4Å" /> '''THE REFINED CRYSTAL S...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:2ctx.jpg|left|200px]]<br /><applet load="2ctx" size=" | + | [[Image:2ctx.jpg|left|200px]]<br /><applet load="2ctx" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2ctx, resolution 2.4Å" /> | caption="2ctx, resolution 2.4Å" /> | ||
'''THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION'''<br /> | '''THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was | + | The crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was refined to an R-factor of 19.5% using 3271 x-ray data to 2.4-A resolution. The polypeptide chain forms three loops, I, II, III, knotted together by four disulfide bridges, with the most prominent, loop II, containing another disulfide close to its lower tip. Loop I is stabilized by one beta-turn and two beta-sheet hydrogen bonds; loop II by eight beta-sheet hydrogen bonds, with the tip folded into two distorted right-handed helical turns stabilized by two alpha-helical and two beta-turn hydrogen bonds; and loop III by hydrophobic interactions and one beta-turn. Loop II and one strand of loop III form an antiparallel triple-pleated beta-sheet, and tight anchoring of the Asn63 side chain fixes the tail segment. In the crystal lattice, the alpha-cobratoxin molecules dimerize by beta-sheet formation between strands 53 and 57 of symmetry-related molecules. Because such interactions are found also in a cardiotoxin and alpha-bungarotoxin, this could be of importance for interaction with acetylcholine receptor. |
==About this Structure== | ==About this Structure== | ||
| - | 2CTX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Naja_naja Naja naja]. Full crystallographic information is available from [http:// | + | 2CTX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Naja_naja Naja naja]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2CTX OCA]. |
==Reference== | ==Reference== | ||
| Line 16: | Line 16: | ||
[[Category: Lange, G.]] | [[Category: Lange, G.]] | ||
[[Category: Maelicke, A.]] | [[Category: Maelicke, A.]] | ||
| - | [[Category: Pal, G | + | [[Category: Pal, G P.]] |
[[Category: Saenger, W.]] | [[Category: Saenger, W.]] | ||
| - | [[Category: Wilson, K | + | [[Category: Wilson, K S.]] |
[[Category: neurotoxin]] | [[Category: neurotoxin]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:52:30 2008'' |
Revision as of 14:52, 21 February 2008
|
THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION
Overview
The crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was refined to an R-factor of 19.5% using 3271 x-ray data to 2.4-A resolution. The polypeptide chain forms three loops, I, II, III, knotted together by four disulfide bridges, with the most prominent, loop II, containing another disulfide close to its lower tip. Loop I is stabilized by one beta-turn and two beta-sheet hydrogen bonds; loop II by eight beta-sheet hydrogen bonds, with the tip folded into two distorted right-handed helical turns stabilized by two alpha-helical and two beta-turn hydrogen bonds; and loop III by hydrophobic interactions and one beta-turn. Loop II and one strand of loop III form an antiparallel triple-pleated beta-sheet, and tight anchoring of the Asn63 side chain fixes the tail segment. In the crystal lattice, the alpha-cobratoxin molecules dimerize by beta-sheet formation between strands 53 and 57 of symmetry-related molecules. Because such interactions are found also in a cardiotoxin and alpha-bungarotoxin, this could be of importance for interaction with acetylcholine receptor.
About this Structure
2CTX is a Single protein structure of sequence from Naja naja. Full crystallographic information is available from OCA.
Reference
The refined crystal structure of alpha-cobratoxin from Naja naja siamensis at 2.4-A resolution., Betzel C, Lange G, Pal GP, Wilson KS, Maelicke A, Saenger W, J Biol Chem. 1991 Nov 15;266(32):21530-6. PMID:1939183
Page seeded by OCA on Thu Feb 21 16:52:30 2008
