Sandbox 34: Difference between revisions

There are many inhibitors for papain because of its broad specificity. It is often used as a model enzyme for those in the papain superfamily, such as cathepsin L and cathepsin K. The inhibition of papain is usually due to active site restriction of cysteine-25 and histidine-159. An interesting inhibitor for cathepsin L developed using papain as the model protease is that of <scene name='Sandbox_34/Clik148_inhibitor/1'>Clik148</scene>. This inhibitor uses both prime and non-prime sites to inhibit papain.<ref> PMID:10600517 </ref> In two different cathepsin K inhibitors, referenced PDB codes <scene name='Sandbox_34/Cathepsin_k_1bp4/1'>1BP4</scene> and <scene name='Sandbox_34/Cathepsin_k_1bqi/1'>1BQI</scene>, it is evident that the inhibitor binds with much closer proximity than that of Clik148.<ref> PMID:9804696 </ref> Other inhibitors, such as <scene name='Sandbox_34/Pap_1stf/1'>human stefin B</scene>, illustrated in magenta, are much more complex in their <scene name='Sandbox_34/Pap_1stf/2'>inhibition</scene>. The human stefin B molecule has a five stranded beta-sheet the wraps around a five turn alpha-helix. Through this study, Stubbs et al. were able to conclude that cysteine proteinase inhibitors are "fundamentally different to [those] observed for serine proteinase inhibitors."<ref>PMID:2347312</ref>