Three Dimensional Solution Structure of Neurotoxin CM-11 from the Ophiophagus hannah.

ABSTRACT

The Ophiophagus hannah (King Cobra) neurotoxin CM-11 is a small protein with 72 amino acid residues. Based on complete assignments of (1)H-NMR resonances and determination of secondary structures of CM-11, 349 distance and 27 dihedral angle constraints including 19 psi's and 8 Xi (1)'s were collected from NOESY and DQF-COSY, and the chemical stereospecific assignment of Beta(1)H was partially achieved. Twelve structures with lower energy were obtained via metric matrix distance geometry and refinement with simulated annealing. These structures have a low RMSD of 0.14 nm for backbone atoms and 0.20 nm for heavy atoms, with no distance constraint violation more than 0.05 nm, and no dihedral angle violation more than 3deg;.