th  - 1987 - 51st ENC Conference

MKI9
SEQUENTIAL INDIVIDUAL 1H NMR RESONANCES ASSIGNMENTS
OF CARDIOTOXIN III FROM FORMOSAN COBRA VENOM
(NaSa naja atra)
• +
C. Yu and T. H. Hseu
Department of Chemistry, National Tsing Hua University,
Hsinchu, Taiwan*
Department of Life Science, National Tsing Hua
University, Hsinchu, Taiwan +
Cardiotoxin III is one of the membrane active proteins
from Formosan cobra (Naja naja atra). It is a small basic
single polypeptide consisting of 60 amino acid residues
cross-linked by four disulfide bonds. The most characte-
rized biological activity of cardiotoxins is the in vitro
hemolysis of erythocytes. Nonetheless, details about the
mechanism of cardiotoxin hemolysis remain inconclusive.
Knowledge of the molecular conformation of cardiotoxins
might be informative with regard to this common feature of
functional properties of all toxins in this class. The
assignments of IH NMR resonances is the first first step to
probe the structure-functional relationship of carditoxin.
The result of sequential assignment of IH NMR spectrum
for cardiotoxin III from naja naja atra is presented. The
assignments are based entirly on the amino acid sequence and
2D NMR experiment on 400 MHz. The measurements were done in
both H20 and D20. Phase-sensitive and double quantum filter-
ing 2D techniques combined with solvent elimination routine
proved to be useful, particularly those cross peaks closed to
diagnol area (e.g. phe-13 and phe-25). The pH tetration
curves were consistent with the aromatic resonances assigments
of cardiotoxin III by 2D experiments.