A novel short neurotoxin, cobrotoxin c, from monocellate cobra (Naja kaouthia) venom: isolation and purification, primary and secondary structure determination, and tertiary structure modeling.
A novel short neurotoxin, cobrotoxin c (CBT C) was isolated from the venom of monocellate cobra (Naja kaouthia) using a combination of ion-exchange chromatography and FPLC. Its primary structure was determined by Edman degradation. CBT C is composed of 61 amino acid residues. It differs from cobrotoxin b (CBT B) by only two amino acid substitutions, Thr/Ala11 and Arg/Thr56, which are not located on the functionally important regions by sequence similarity. However, the LD50 is 0.08 mg/g to mice, i.e. approximately five-fold higher than for CBT B. Strikingly, a structure-function relationship analysis suggests the existence of a functionally important domain on the outside of Loop III of CBT C. The functionally important basic residues on the outside of Loop III might have a pairwise interaction with alpha subunit, instead of gamma or delta subunits of the nicotinic acetylcholine receptor (nAChR).
Meng
Qing-Xiong
QX
Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, PR China.
Wang
Wan-Yu
WY
Lu
Qiu-Min
QM
Jin
Yang
Y
Wei
Ji-Fu
JF
Zhu
Shao-Wen
SW
Xiong
Yu-Liang
YL
D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003039:Cobra Neurotoxin Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D017815:Elapidae; D007928:Lethal Dose 50; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017385:Sequence Homology; D013329:Structure-Activity Relationship
D003039:Cobra Neurotoxin Proteins