Ann taylor sandbox 2: Difference between revisions

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Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

Ann Taylor, Jonathon Logan Anderson

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 The transition state analogue held in place mostly by polar interactions.  The ribose group is close to the opening of the pocket, with the purine portion deeper in the pocket, close to the zinc.  Nine hydrogen bonds stabilize the transition state-enzyme complex.
-ADA is very stereoselective for the 6R isomer.  This specificity is due to the location of the catalytic zinc, <scene name='36/365335/Asp/3'>ASP 295</scene> and <scene name='36/365335/His_238/1'>HIS 238</scene>.  Interestingly, one face of the purine ring is exposed to polar groups and zinc, while the other face is only exposed to nonpolar residues.  The proposed catalytic mechanism has ASP 295 act as a general base, while the zinc acts as an electrophile to activate the water molecule.  His 238 orients the water and stabilizes the charge of the attacking hydroxide.  The protonated Glu217 or the water hydrogen bonded to it could donate or share a proton with the N1 of the substrate.
+ADA is very stereoselective for the 6R isomer.  This specificity is due to the location of the catalytic zinc, <scene name='36/365335/Asp_295/1'>ASP 295</scene> and <scene name='36/365335/His_238/1'>HIS 238</scene>.  Interestingly, one face of the purine ring is exposed to polar groups and zinc, while the other face is only exposed to nonpolar residues.  The proposed catalytic mechanism has ASP 295 act as a general base, while the zinc acts as an electrophile to activate the water molecule.  His 238 orients the water and stabilizes the charge of the attacking hydroxide.  The protonated Glu217 or the water hydrogen bonded to it could donate or share a proton with the N1 of the substrate.
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