Papain ligands

Hansch, C. and Calef, D.F. (1976). Structure-Activity Relationships in Papain-Ligand Interactions. J.Org.Chem., 41,1240-1243. 

Hansch C, Calef DF. Structure-activity relationships in papain-ligand interactions. J Org Chem 1976 41 1240-1243. 

When the target enzyme is difficult to obtain, related enzymes could be used to provide insights in the design of novel ligands. For example, papain was used to design a class of potent cathepsin K inhibitors [33] spanning both sides of the papain active site. However, fine-tuning these inhibitors to produce more potent ones required the use of the crystal structure of cathepsin K itself [34],... 

Chen TX, Nie HL, Li SB, Branford-White C, Su SN, Zhu LM. Comparison Adsorption of papain using immohilized dye ligands on affinity membranes. Colloids Surf. B Biointerfaces 2009 72 25-31. 

Desjarlais et al. expanded these ideas to include molecular flexibility. This was done by breaking the ligand into parts that overlap at the rotatable bonds, separately docking the parts, and finally checking to see if the parts could be reassembled into the molecule. They also searched a database of small molecules to find struaures that could be modified into inhibitors of papain or carbonic anhydrase. ... 

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