2CTX

THE REFINED CRYSTAL STRUCTURE OF ALPHA-COBRATOXIN FROM NAJA NAJA SIAMENSIS AT 2.4-ANGSTROMS RESOLUTION

Summary for 2CTX

• Entry DOI: 10.2210/pdb2ctx/pdb
• Descriptor: ALPHA-COBRATOXIN (2 entities in total)
• Functional Keywords: neurotoxin
• Biological source: Naja naja (Indian cobra)
• Cellular location: Secreted {ECO:0000269|Ref: P25671
• Total number of polymer chains: 1
• Total formula weight: 7842.09

Authors

Betzel, C.,Lange, G.,Pal, G.P.,Wilson, K.S.,Maelicke, A.,Saenger, W. (deposition date: 1991-09-24, release date: 1993-10-31, Last modification date: 2024-11-06)

Primary citation

Betzel, C.,Lange, G.,Pal, G.P.,Wilson, K.S.,Maelicke, A.,Saenger, W.
The refined crystal structure of alpha-cobratoxin from Naja naja siamensis at 2.4-A resolution.
J.Biol.Chem., 266:21530-21536, 1991

PubMed Abstract: 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.

PubMed: 1939183

Experimental method

X-RAY DIFFRACTION (2.4 Å)