Weak Versus Low Affinity The Importance of Ligand Efficiency

2 Weak Versus Low Affinity The Importance of Ligand Efficiency 

Is an ant weak Anyone who has casually squashed one that has invaded their picnic will probably say yes. However, if you watch an ant escaping with a crumb, the answer is not so obvious ants can carry at least ten times their own body weight. This is akin to the situation with fragments they may have low absolute affinities, but often bind tightly for their size. The question is how to properly measure binding affinity in light of molecular weight. 

Probably the most widely used metric is called ligand efficiency, or LE. It was first proposed as a brief letter in Drug Discovery Today by Andrew Hopkins and coworkers [78]  

LE = (free energy of ligand binding)/(number of heavy atoms) 

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