主题：【原创】中药小故事之八——全蝎 -- 快刀浪子

This protein is scorpion toxin II from Androctonus austalis. It is a 64 residue protein that binds to mammalian sodium channels, causing paralysis and death at high enough doses. Most of the residues indicated to be crucial to binding to sodium channels are located on a knob at the lower left of the image. Positively charged amino acids are shown in red. Arg 62 and His 64 protrude furthest from the core of the protein. It is reasonable to expect such residues to be involved in binding to sodium channels, which usually handle positively-charged Na+ ions. Mutational analysis has shown that Asp 8 (blue) and Lys 58 (green) are likely to be critical to binding. Arg 18 is not in the same region as the rest of the binding residues, but probably has a major role in binding also. The purple segment is residues 9 through 12, which together with residue 8, form a structurally conserved loop found in many scorpion toxins. This image was made by J High, School of Biology, Georgia Tech, 1998.