title: Characterization of a partially structured state in an all-beta-sheet protein.
abstract: Cardiotoxin analogue III (CTX III) is a low-molecular-mass all-beta-sheet protein isolated from the Taiwan cobra (Naja naja atra) venom. A stable partially structured state similar to the "molten globule' state has been identified for CTX III in a 3% (w/v) solution of 2,2,2-trichloroacetic acid at 298 K. This stable state has been structurally characterized using a variety of techniques such as CD, 1-anilinonaphthalene-8-sulphonate fluorescence binding, Fourier transform IR and two-dimensional NMR spectroscopy techniques. Direct assignment of the homonuclear two-dimensional NMR spectra of the protein in 3% trichloroacetic acid showed that drastic structural perturbation had not taken place in the protein and that the 'intermediate' state retained a significant portion of the native secondary-structural interactions. It is found that about 65% of the native beta-sheet structural contacts are maintained in the partially structured state of CTX III in 3% trichloroacetic acid.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors.forename: T
authors.initials: T
authors.lastname: Sivaraman
authors.forename: T K
authors.initials: TK
authors.lastname: Kumar
authors.forename: G
authors.initials: G
authors.lastname: Jayaraman
authors.forename: C C
authors.initials: CC
authors.lastname: Han
authors.forename: C
authors.initials: C
authors.lastname: Yu
mesh_terms: D002942:Circular Dichroism; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry*; D004546:Elapid Venoms / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship; D014238:Trichloroacetic Acid
chemical_list: D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D012996:Solutions; C082202:cardiotoxin III, Naja naja atra; D014238:Trichloroacetic Acid