1tmm

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[[Image:1tmm.gif|left|200px]]
[[Image:1tmm.gif|left|200px]]
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{{Structure
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<!--
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|PDB= 1tmm |SIZE=350|CAPTION= <scene name='initialview01'>1tmm</scene>, resolution 1.25&Aring;
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The line below this paragraph, containing "STRUCTURE_1tmm", creates the "Structure Box" on the page.
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|SITE=
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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|LIGAND= <scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=APC:DIPHOSPHOMETHYLPHOSPHONIC+ACID+ADENOSYL+ESTER'>APC</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=HHR:6-HYDROXYMETHYLPTERIN'>HHR</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/2-amino-4-hydroxy-6-hydroxymethyldihydropteridine_diphosphokinase 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.6.3 2.7.6.3] </span>
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or leave the SCENE parameter empty for the default display.
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|GENE= FOLK, B0142 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
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-->
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|DOMAIN=
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{{STRUCTURE_1tmm| PDB=1tmm | SCENE= }}
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|RELATEDENTRY=[[1hka|1HKA]], [[1eqm|1EQM]], [[1q0n|1Q0N]], [[1eq0|1EQ0]], [[1ex8|1EX8]], [[1cbk|1CBK]], [[1dy3|1DY3]], [[1f9y|1F9Y]], [[1f9h|1F9H]], [[1g4c|1G4C]], [[1hq2|1HQ2]], [[1im6|1IM6]], [[1kbr|1KBR]], [[1ru2|1RU2]], [[1ru1|1RU1]], [[1rtz|1RTZ]], [[1rb0|1RB0]], [[1tmj|1TMJ]]
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1tmm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tmm OCA], [http://www.ebi.ac.uk/pdbsum/1tmm PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1tmm RCSB]</span>
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}}
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'''Crystal structure of ternary complex of E.coli HPPK(W89A) with MGAMPCPP and 6-Hydroxymethylpterin'''
'''Crystal structure of ternary complex of E.coli HPPK(W89A) with MGAMPCPP and 6-Hydroxymethylpterin'''
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[[Category: 6-hydroxymethyl-7,8-dihydropterin]]
[[Category: 6-hydroxymethyl-7,8-dihydropterin]]
[[Category: 6-hydroxymethylpterin]]
[[Category: 6-hydroxymethylpterin]]
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[[Category: antimicrobial agent]]
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[[Category: Antimicrobial agent]]
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[[Category: catalytic mechanism]]
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[[Category: Catalytic mechanism]]
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[[Category: drug design]]
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[[Category: Drug design]]
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[[Category: folate]]
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[[Category: Folate]]
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[[Category: hppk]]
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[[Category: Hppk]]
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[[Category: product release]]
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[[Category: Product release]]
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[[Category: pterin]]
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[[Category: Pterin]]
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[[Category: pyrophosphokinase]]
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[[Category: Pyrophosphokinase]]
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[[Category: pyrophosphoryl transfer]]
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[[Category: Pyrophosphoryl transfer]]
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[[Category: substrate specificity]]
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[[Category: Substrate specificity]]
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[[Category: ternary complex]]
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[[Category: Ternary complex]]
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[[Category: x-ray crystallography]]
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[[Category: X-ray crystallography]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 10:08:03 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 23:58:12 2008''
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Revision as of 07:08, 3 May 2008

Image:1tmm.gif

Template:STRUCTURE 1tmm

Crystal structure of ternary complex of E.coli HPPK(W89A) with MGAMPCPP and 6-Hydroxymethylpterin


Overview

Deletion mutagenesis, biochemical, and X-ray crystallographic studies have shown that loop 3 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is required for the assembly of the active center, plays an important role in the stabilization of the ternary complex of HPPK with MgATP and 6-hydroxymethyl-7,8-dihydropterin (HP), and is essential for catalysis. Whether the critical functional importance of loop 3 is due to the interactions between residues R84 and W89 and the two substrates has been addressed by site-directed mutagenesis, biochemical, and X-ray crystallographic studies. Substitution of R84 with alanine causes little changes in the dissociation constants and kinetic constants of the HPPK-catalyzed reaction, indicating that R84 is not important for either substrate binding or catalysis. Substitution of W89 with alanine increases the K(d) for the binding of MgATP by a factor of 3, whereas the K(d) for HP increases by a factor of 6, which is due to the increase in the dissociation rate constant. The W89A mutation decreases the rate constant for the chemical step of the forward reaction by a factor of 15 and the rate constant for the chemical step of the reverse reaction by a factor of 25. The biochemical results of the W89A mutation indicate that W89 contributes somewhat to the binding of HP and more significantly to the chemical step. The crystal structures of W89A show that W89A has different conformations in loops 2 and 3, but the critical catalytic residues are positioned for catalysis. When these results are taken together, they suggest that the critical functional importance of loop 3 is not due to the interactions of the R84 guanidinium group or the W89 indole ring with the substrates.

About this Structure

1TMM is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Is the critical role of loop 3 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase in catalysis due to loop-3 residues arginine-84 and tryptophan-89? Site-directed mutagenesis, biochemical, and crystallographic studies., Li Y, Blaszczyk J, Wu Y, Shi G, Ji X, Yan H, Biochemistry. 2005 Jun 21;44(24):8590-9. PMID:15952765 Page seeded by OCA on Sat May 3 10:08:03 2008

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