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2mas
From Proteopedia
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[[Image:2mas.gif|left|200px]] | [[Image:2mas.gif|left|200px]] | ||
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'''PURINE NUCLEOSIDE HYDROLASE WITH A TRANSITION STATE INHIBITOR''' | '''PURINE NUCLEOSIDE HYDROLASE WITH A TRANSITION STATE INHIBITOR''' | ||
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[[Category: Sacchettini, J C.]] | [[Category: Sacchettini, J C.]] | ||
[[Category: Schramm, V L.]] | [[Category: Schramm, V L.]] | ||
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Inosine]] |
| - | [[Category: | + | [[Category: Iu-nh]] |
| - | [[Category: | + | [[Category: Purine nucleosidase]] |
| - | [[Category: | + | [[Category: Purine nucleoside hydrolase]] |
| - | [[Category: | + | [[Category: Uridine]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 09:31:46 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 06:31, 4 May 2008
PURINE NUCLEOSIDE HYDROLASE WITH A TRANSITION STATE INHIBITOR
Overview
Nucleoside N-ribohydrolases are targets for disruption of purine salvage in the protozoan parasites. The structure of a trypanosomal N-ribohydrolase in complex with a transition-state inhibitor is reported at 2.3 A resolution. The nonspecific nucleoside hydrolase from Crithidia fasciculata cocrystallized with p-aminophenyliminoribitol reveals tightly bound Ca2+ as a catalytic site ligand. The complex with the transition-state inhibitor is characterized by (1) large protein conformational changes to create a hydrophobic leaving group site (2) C3'-exo geometry for the inhibitor, typical of a ribooxocarbenium ion (3) stabilization of the ribooxocarbenium analogue between the neighboring group 5'-hydroxyl and bidentate hydrogen bonds to Asn168; and (4) octacoordinate Ca2+ orients a catalytic site water and is liganded to two hydroxyls of the inhibitor. The mechanism is ribooxocarbenium stabilization with weak leaving group activation and is a departure from glucohydrolases which use paired carboxylates to achieve the transition state.
About this Structure
2MAS is a Single protein structure of sequence from Crithidia fasciculata. Full crystallographic information is available from OCA.
Reference
Trypanosomal nucleoside hydrolase. A novel mechanism from the structure with a transition-state inhibitor., Degano M, Almo SC, Sacchettini JC, Schramm VL, Biochemistry. 1998 May 5;37(18):6277-85. PMID:9572842 Page seeded by OCA on Sun May 4 09:31:46 2008
