Active sites, indirect mapping

Indirect studies that tried to map the sweet taste active site or to design... 

The nature of the cholinergic receptor has been the subject of considerable study for over 75 years. Aspects of its shape, conformations, and active sites have, over the years, slowly and enticingly revealed themselves to our prying. The efforts were initially by empirical-intuitive methods, then by SAR analogies, receptor mapping, and other indirect methods. Generous applications of X-ray crystallography and molecular receptor probes followed, and most recently, the actual isolation of the active receptor preparations were achieved. 

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