Artificial Receptors: molecular imprints discern closely related toxins

We describe silane molecular imprints which can discriminate closely relate d toxins, supporting the potential usefulness of molecular imprints as arti ficial receptors, i.e., sensing elements, for detection of biological toxin s. Molecular imprints to N-acetylated mu-Conotoxin GIIIB (NacGIIIB) were pr epared and binding assays carried out using [C-14]-NacGIIIB. In accordance with a Type I Langmuir adsorption isotherm, saturation of NacGIIIB imprint binding sites occurred at approximately 6.25 mu M and Scatchard analysis re vealed a relatively high binding affinity (K-d = 0.37 nM). Binding assays c arried out in the presence of a 10-fold molar excess of unlabeled ligand (N acGIIIB) indicated a significant decrease in bound [C-14]-NacGIIIB, i.e., > 90%. In contrast, incubation of [C-14]-NacGIIIB with GIIIA or GIIIB as wel l as a variety of other Conotoxins demonstrated no significant competition. However, NacGIIIB's closest congener, i.e., NacGIIIA, competed, but requir ed a higher concentration (K-0.5 congruent to 12.5 mu M) to achieve 50% red uction in binding of [C-14]-NacGIIIB than that observed for NacGIIIB (K-0.5 congruent to 6.25 mu M) These results suggest that simple silane imprints can discern subtle differences in tertiary structure of closely related sma ll proteins. (C) 2000 Elsevier Science S.A. All rights reserved.