2ctx
From Proteopedia
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 Sat May 3 23:03:12 2008
