1mas: Difference between revisions
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[[Image:1mas.jpg|left|200px]] | [[Image:1mas.jpg|left|200px]] | ||
'''PURINE NUCLEOSIDE HYDROLASE''' | {{Structure | ||
|PDB= 1mas |SIZE=350|CAPTION= <scene name='initialview01'>1mas</scene>, resolution 2.5Å | |||
|SITE= <scene name='pdbsite=ACT:Pocket+At+The+C-Terminal+End+Of+Beta+Sheet'>ACT</scene> | |||
|LIGAND= <scene name='pdbligand=K:POTASSIUM ION'>K</scene> | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Purine_nucleosidase Purine nucleosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.1 3.2.2.1] | |||
|GENE= IU-NH FROM C.FASCICULATA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=5656 Crithidia fasciculata]) | |||
}} | |||
'''PURINE NUCLEOSIDE HYDROLASE''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1MAS is a [ | 1MAS is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Crithidia_fasciculata Crithidia fasciculata]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MAS OCA]. | ||
==Reference== | ==Reference== | ||
Three-dimensional structure of the inosine-uridine nucleoside N-ribohydrolase from Crithidia fasciculata., Degano M, Gopaul DN, Scapin G, Schramm VL, Sacchettini JC, Biochemistry. 1996 May 14;35(19):5971-81. PMID:[http:// | Three-dimensional structure of the inosine-uridine nucleoside N-ribohydrolase from Crithidia fasciculata., Degano M, Gopaul DN, Scapin G, Schramm VL, Sacchettini JC, Biochemistry. 1996 May 14;35(19):5971-81. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8634238 8634238] | ||
[[Category: Crithidia fasciculata]] | [[Category: Crithidia fasciculata]] | ||
[[Category: Purine nucleosidase]] | [[Category: Purine nucleosidase]] | ||
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[[Category: purine nucleoside hydrolase]] | [[Category: purine nucleoside hydrolase]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 12:41:10 2008'' | ||
Revision as of 13:41, 20 March 2008
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| , resolution 2.5Å | |||||||
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| Sites: | |||||||
| Ligands: | |||||||
| Gene: | IU-NH FROM C.FASCICULATA (Crithidia fasciculata) | ||||||
| Activity: | Purine nucleosidase, with EC number 3.2.2.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
PURINE NUCLEOSIDE HYDROLASE
OverviewOverview
Protozoan parasites rely on the host for purines since they lack a de novo synthetic pathway. Crithidia fasciculata salvages exogenous inosine primarily through hydrolysis of the N-ribosidic bond using several nucleoside hydrolases. The most abundant nucleoside hydrolase is relatively nonspecific but prefers inosine and uridine as substrates. Here we report the three-dimensional structure of the inosine-uridine nucleoside hydrolase (IU-NH) from C. fasciculata determined by X-ray crystallography at a nominal resolution of 2.5 A. The enzyme has an open (alpha, beta) structure which differs from the classical dinucleotide binding fold. IU-nucleoside hydrolase is composed of a mixed eight-stranded beta sheet surrounded by six alpha helices and a small C-terminal lobe composed of four alpha helices. Two short antiparallel beta strands are involved in intermolecular contacts. The catalytic pocket is located at the C-terminal end of beta strands beta 1 and beta 4. Four aspartate residues are located at the bottom of the cavity in a geometry which suggests interaction with the ribose moiety of the nucleoside. These groups could provide the catalytically important interactions to the ribosyl hydroxyls and the stabilizing anion for the oxycarbonium-like transition state. Histidine 241, located on the side of the active site cavity, is the proposed proton donor which facilitates purine base departure [Gopaul, D. N., Meyer, S. L., Degano, M., Sacchettini, J. C., & Schramm, V. L. (1996) Biochemistry 35, 5963-5970]. The substrate binding site is unlike that from purine nucleoside phosphorylase, phosphoribosyltransferases, or uracil DNA glycosylase and thus represents a novel architecture for general acid-base catalysis. This detailed knowledge of the architecture of the active site, together with the previous transition state analysis [Horenstein, B. A., Parkin, D. W., Estupinan, B., & Schramm, V. L. (1991) Biochemistry 30, 10788-10795], allows analysis of the interactions leading to catalysis and an explanation for the tight-binding inhibitors of the enzyme [Schramm, V. L., Horenstein, B. A., & Kline, P. C. (1994) J. Biol. Chem. 269, 18259-18262].
About this StructureAbout this Structure
1MAS is a Single protein structure of sequence from Crithidia fasciculata. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure of the inosine-uridine nucleoside N-ribohydrolase from Crithidia fasciculata., Degano M, Gopaul DN, Scapin G, Schramm VL, Sacchettini JC, Biochemistry. 1996 May 14;35(19):5971-81. PMID:8634238
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