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| {{STRUCTURE_1kba| PDB=1kba | SCENE= }} | | {{STRUCTURE_1kba| PDB=1kba | SCENE= }} |
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| '''CRYSTAL STRUCTURE OF KAPPA-BUNGAROTOXIN AT 2.3-ANGSTROM RESOLUTION'''
| | ===CRYSTAL STRUCTURE OF KAPPA-BUNGAROTOXIN AT 2.3-ANGSTROM RESOLUTION=== |
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| ==Overview==
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| kappa-Neurotoxins display a very low affinity for neuromuscular receptors, but bind tightly to, and inhibit, nicotinic acetylcholine receptors in neuronal tissue such as the chick ciliary ganglia. In contrast, alpha-neurotoxins bind with high affinity and inhibit nicotinic acetylcholine receptors at the neuromuscular junction. The origin of this difference in specificity has been a long-studied question in the field. Here we report the first crystal structure of a kappa-neurotoxin, kappa-bungarotoxin. Unlike the NMR structure previously reported [Sutcliffe, M. J., Dobson, C. M., & Oswald, R. E. (1992) Biochemistry 31, 2962-2970], the present crystal structure more accurately defines the polypeptide fold and the nature of the interaction between subunits in the active dimer, which is a unique feature of the kappa-neurotoxins. The structure has been refined to R = 19.6% with X-ray diffraction data extending to a resolution of 2.3 A. There are two independent protein molecules (66 amino acid residues each) in the asymmetric unit that are arranged as a dimer with the two subunits related by a rotation of 178.6 degrees. Each subunit consists of three main-chain loops. Three of the five beta-strands of each subunit form an antiparallel beta-sheet which becomes an extended six-stranded antiparallel beta-sheet, by virtue of the approximate 2-fold symmetry of the dimer. The interactions at the dimer interface consist of six main-chain-main-chain hydrogen bonds, as well as three other hydrogen-bonding interactions involving side chains.(ABSTRACT TRUNCATED AT 250 WORDS)
| | The line below this paragraph, {{ABSTRACT_PUBMED_7947721}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 7947721 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_7947721}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Sacchettini, J C.]] | | [[Category: Sacchettini, J C.]] |
| [[Category: Toxin]] | | [[Category: Toxin]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:31:58 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 10:04:32 2008'' |
