Primary structure of ammodytoxin C further reveals the toxic site of ammodytoxin.
The sequence of ammodytoxin C, a presynaptically toxic, basic phospholipase A2 of Vipera ammodytes ammodytes venom was determined. The toxin differs only in two amino acid residues from the most toxic isotoxin ammodytoxin A and is 18-times less lethal. Ammodytoxin B which is 30-times less lethal than ammodytoxin A differs from it only in three amino acid residues. From the three-dimensional model of ammodytoxin A, it can be seen that mutated regions of ammodytoxin B and ammodytoxin C are on the surface, and relatively distant from each other. The observed decrease in toxicity of ammodytoxin C could be a consequence of changed charge in position 128 where a Lys is exchanged for Glu. The resulting change in electrostatic properties of the molecule which influences the orientation of the molecule during the approach to the charged nerve-terminal membrane might be responsible for the observed decrease in toxicity.
Krizaj
I
I
Department of Biochemistry, J. Stefan Institute, Ljubljana, Yugoslavia.
Turk
D
D
Ritonja
A
A
Gubensek
F
F
D000595:Amino Acid Sequence; D000818:Animals; D054501:Group II Phospholipases A2; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D011487:Protein Conformation; D012689:Sequence Homology, Nucleic Acid; D012984:Software; D014757:Viper Venoms / Q000633:toxicity
D014757:Viper Venoms; D010740:Phospholipases; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; C060161:ammodytoxin C