... Na+channels of central neurons. It is our conclusion that the N-terminal loop preceding the a-helix in scorpiontoxins is one of the determinative domains in the interaction of toxins with the target ion ... analysis, matrix solutions consisting of sinapinic acid, 3,5-dimethoxy-4-hydroxycinnaminic acid,or a-cyano-4-hydroxycinnamic acid, were mixed in a 1 : 1ratiowithsamples,spottedonthetargetandallowedtodry.MASSLYNX(Micromass ... determinants of high affinity binding of a-scor-pion toxin and sea anemone toxin in the S3–S4 extracellular loop in domain IV of the Na+channel a subunit. J. Biol. Chem. 271,1595 0–1 5962.15. Jones,...