A large number of toxins (such as paralytic shellfish toxins, tetrodotoxin and bactrachotoxin) are potentially lethal contaminants in seafood. They are known to act by altering the conductance properties of a well-characterized sodium channel found in muscle and nerve tissues. The objective of this study is to develop an enzyme-linked assay to detect these toxins. Enzyme or coenzyme conjugates of the toxin will be coupled with purified sodium channels for use on displacement assays to quantitate the amount of site 1 sodium channel toxins in the sample. The assay is expected to have a sensitivity comparable to the radioimmunoassys currently used, but will avoid the hazards of handling radioisotopes. It will also have a greatly improved cross-reactivity, thus enabling the detection of any site 1 toxin in a seafood sample. In Phase I, enzyme and coenzyme conjugates of saxitoxin and tetrodotoxin will be prepared and tested in displacement assays using partially purified sodium channels. In Phase II enzyme linked toxins will be compared to radiolabeled toxins for binding affinity to the sodium channel and for sensitivity in assays to detect unlabeled toxins. The toxin assay developed will be extremely useful as screening test for the safety of seafood samples. In addition, the reagents produced may aid in the study of sodium channel function.
