The ability of fragments derived from botulinum neurotoxin (BTx) serotype A to bind to GT1b‐coated plastic wells was investigated and compared with the binding characteristics of the parent ∼ 150‐kDa protein. Although the ∼50‐kDa light chain of BTxA had a marginal binding capacity, the predominant adherence to GT1b‐coated wells was exhibited by the ∼ 50‐kDa carboxy‐terminal half of the ∼ 100‐kDa heavy chain of BTxA; the amino‐terminal half of the heavy chain lacked the ability to bind. Binding to GT1b by BTxA and its fragments was compared with that of tetanus neurotoxin (TTx) and the carboxy‐terminal half of its heavy chain. Binding of BTxA and the C‐terminal half of the heavy chain was optimal in buffers of low ionic strength (μ≤ 0.04 and 0.06, respectively), whereas the heavy chain bound GT1b best at μ≤ 0.10. TTx and the ∼ 50‐kDa C‐terminal half of its ∼ 100‐kDa heavy chain bound GT1b at ionic strengths similar to those of BTxA. Comparison of the binding of BTx serotypes A, B, and E to GT1b (using conditions that were found to be optimal for binding by BTxA) indicated differences in the interaction of the three serotypes with GT1b. Compared with BTxA, adherence to GT1b by serotypes B and E was reduced by ∼60 and ∼90%, respectively. Determination of the IC50 values for GT1b derivatives (molar concentration needed to reduce toxin binding to GT1b by 50%) indicated that (a) the carboxyl moiety of the sialosyl residues is recognized by BTxA and TTx, (b) the lipid segment of GT1b enhances BTxA and TTx binding, and (c) the N‐acetyl groups and C(8)‐C(9) on the sialosyl residues are not essential components of the binding site for BTxA and TTx.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of neurochemistry|
|State||Published - Sep 1991|
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience