Effects of subunit cross-linking on the properties of crotoxin.

Crotoxin was cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. Cross-linked crotoxin had the expected amino-terminal amino acids, amino acid composition, behavior on SDS-PAGE and an 80% reduction of reactable lysine residues. It was also non-toxic, had reduced immunological cross-reactivity toward both poly- and monoclonal antibodies raised to the basic subunit of crotoxin and had lost greater than 95% of its phospholipase activity. Loss of toxicity is due to either subunit cross-linking or the modification of essential residues.