{'fraction_non_alphanumeric': 0.030795551753635585, 'fraction_numerical': 0.006843455945252352, 'mean_word_length': 5.39344262295082, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Variations in binding among several agonists at two stoichiometries of the neuronal, α4β2 nicotinic receptor.

Drug-receptor binding interactions of four agonists, ACh, nicotine, and the smoking cessation compounds varenicline (Chantix) and cytisine (Tabex), have been evaluated at both the 2:3 and 3:2 stoichiometries of the α4β2 nicotinic acetylcholine receptor (nAChR). Previous studies have established that unnatural amino acid mutagenesis can probe three key binding interactions at the nAChR: a cation-π interaction, and two hydrogen-bonding interactions to the protein backbone of the receptor. We find that all drugs make a cation-π interaction to TrpB of the receptor. All drugs except ACh, which lacks an N(+)H group, make a hydrogen bond to a backbone carbonyl, and ACh and nicotine behave similarly in acting as a hydrogen-bond acceptor. However, varenicline is not a hydrogen-bond acceptor to the backbone NH that interacts strongly with the other three compounds considered. In addition, we see interesting variations in hydrogen bonding interactions with cytisine that provide a rationalization for the stoichiometry selectivity seen with this compound.