Evidence for a fast-exchange conformational process in alpha-bungarotoxin.
Anomalous behavior of the post-synaptic protein neurotoxin, alpha-bungarotoxin (alpha-bgt), has been observed during reverse-phase HPLC. Purified samples of this toxin from two distinct sources elute from reverse-phase columns as two separate peaks. The protein species represented by these two peaks are in rapid equilibrium, the relative ratio of which displays a pH dependency with a pKa of approximately 3. This equilibrium does not involve the dimerization or aggregation of the toxin and appears to be relatively unique to alpha-bungarotoxin in that similar behavior is not displayed by several other available alpha-neurotoxins. pH-dependent conformational changes have been documented for several alpha-neurotoxins whose crystal structures have been determined (alpha-bungarotoxin, alpha-cobratoxin, and erabutoxin b). One or more of these may account for the observed behavior of alpha-bungarotoxin on reverse-phase HPLC.
Fiordalisi
J J
JJ
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110.
Grant
G A
GA
D000595:Amino Acid Sequence; D002038:Bungarotoxins / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D002038:Bungarotoxins