Structure-Activity Relationships and Immunochemical Studies on Cobrotoxin
Abstract
The status of free amino groups in cobrotoxin was studied by stepwise modification with trinitrobenzene sulfonate. Lys-27 was selectively modified without altering the activity of cobrotoxin. However, complete loss of the activity was observed when Lys-27 and Lys-47 were trinitrophenylated, suggesting that the epsilon-amino group of Lys-47 is essential for the activity of cobrotoxin. The alpha-amino group of N-terminal leucine had not any correlation with activity was demonstrated by guanidination of the lysine residues with O- methylisourea followed by trinitrophenylation of the alpha-amino group. The carboxyl groups in cobrotoxin were modified with glycine methyl ester after activation with water-soluble carbodiimide. Six out of seven free carboxyls reacted in the absence of guanidine-HCl without altering the biological activity. When the remaining carboxyl was modified in the presence of 5 M guanidine-HCl, the resulting toxin was devoid of activity. This 'buried' carboxyl is essential for activity and was identified as the gamma-carboxyl group of Glu-21.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1971
- Accession Number
- AD0732480
Entities
People
- Chen-chung Yang
Organizations
- Kaohsiung Medical University