3tim
From Proteopedia
(New page: 200px<br /><applet load="3tim" size="450" color="white" frame="true" align="right" spinBox="true" caption="3tim, resolution 2.8Å" /> '''THE CRYSTAL STRUCTURE...) |
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| - | [[Image:3tim.jpg|left|200px]]<br /><applet load="3tim" size=" | + | [[Image:3tim.jpg|left|200px]]<br /><applet load="3tim" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="3tim, resolution 2.8Å" /> | caption="3tim, resolution 2.8Å" /> | ||
'''THE CRYSTAL STRUCTURE OF THE "OPEN" AND THE "CLOSED" CONFORMATION OF THE FLEXIBLE LOOP OF TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE'''<br /> | '''THE CRYSTAL STRUCTURE OF THE "OPEN" AND THE "CLOSED" CONFORMATION OF THE FLEXIBLE LOOP OF TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Triosephosphate isomerase has an important loop near the active site which | + | Triosephosphate isomerase has an important loop near the active site which can exist in a "closed" and in an "open" conformation. Here we describe the structural properties of this "flexible" loop observed in two different structures of trypanosomal triosephosphate isomerase. Trypanosomal triosephosphate isomerase, crystallized in the presence of 2.4 M ammonium sulfate, packs as an asymmetric dimer of 54,000 Da in the crystallographic asymmetric unit. Due to different crystal contacts, peptide 167-180 (the flexible loop of subunit-1) is an open conformation, whereas in subunit-2, this peptide (residues 467-480) is in a closed conformation. In the closed conformation, a hydrogen bond exists between the tip of the loop and a well-defined sulfate ion which is bound to the active site of subunit-2. Such an active site sulfate is not present in subunit-1 due to crystal contacts. When the native (2.4 M ammonium sulfate) crystals are transferred to a sulfate-free mother liquor, the flexible loop of subunit-2 adopts the open conformation. From a closed starting model, this open conformation was discovered through molecular dynamics refinement without manual intervention, despite involving C alpha shifts of up to 7 A. The tip of the loop, residues 472, 473, 474, and 475, moves as a rigid body. Our analysis shows that in this crystal form the flexible loop of subunit-2 faces a solvent channel. Therefore the open and the closed conformations of this flexible loop are virtually unaffected by crystal contacts. The actual observed conformation depends only on the absence or presence of a suitable ligand in the active site. |
==About this Structure== | ==About this Structure== | ||
| - | 3TIM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trypanosoma_brucei_brucei Trypanosoma brucei brucei]. Active as [http://en.wikipedia.org/wiki/Triose-phosphate_isomerase Triose-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.1 5.3.1.1] Full crystallographic information is available from [http:// | + | 3TIM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Trypanosoma_brucei_brucei Trypanosoma brucei brucei]. Active as [http://en.wikipedia.org/wiki/Triose-phosphate_isomerase Triose-phosphate isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.1 5.3.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3TIM OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Triose-phosphate isomerase]] | [[Category: Triose-phosphate isomerase]] | ||
[[Category: Trypanosoma brucei brucei]] | [[Category: Trypanosoma brucei brucei]] | ||
| - | [[Category: Wierenga, R | + | [[Category: Wierenga, R K.]] |
[[Category: isomerase(intramolecular oxidoreductse)]] | [[Category: isomerase(intramolecular oxidoreductse)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:11:37 2008'' |
Revision as of 17:11, 21 February 2008
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THE CRYSTAL STRUCTURE OF THE "OPEN" AND THE "CLOSED" CONFORMATION OF THE FLEXIBLE LOOP OF TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE
Overview
Triosephosphate isomerase has an important loop near the active site which can exist in a "closed" and in an "open" conformation. Here we describe the structural properties of this "flexible" loop observed in two different structures of trypanosomal triosephosphate isomerase. Trypanosomal triosephosphate isomerase, crystallized in the presence of 2.4 M ammonium sulfate, packs as an asymmetric dimer of 54,000 Da in the crystallographic asymmetric unit. Due to different crystal contacts, peptide 167-180 (the flexible loop of subunit-1) is an open conformation, whereas in subunit-2, this peptide (residues 467-480) is in a closed conformation. In the closed conformation, a hydrogen bond exists between the tip of the loop and a well-defined sulfate ion which is bound to the active site of subunit-2. Such an active site sulfate is not present in subunit-1 due to crystal contacts. When the native (2.4 M ammonium sulfate) crystals are transferred to a sulfate-free mother liquor, the flexible loop of subunit-2 adopts the open conformation. From a closed starting model, this open conformation was discovered through molecular dynamics refinement without manual intervention, despite involving C alpha shifts of up to 7 A. The tip of the loop, residues 472, 473, 474, and 475, moves as a rigid body. Our analysis shows that in this crystal form the flexible loop of subunit-2 faces a solvent channel. Therefore the open and the closed conformations of this flexible loop are virtually unaffected by crystal contacts. The actual observed conformation depends only on the absence or presence of a suitable ligand in the active site.
About this Structure
3TIM is a Single protein structure of sequence from Trypanosoma brucei brucei. Active as Triose-phosphate isomerase, with EC number 5.3.1.1 Full crystallographic information is available from OCA.
Reference
The crystal structure of the "open" and the "closed" conformation of the flexible loop of trypanosomal triosephosphate isomerase., Wierenga RK, Noble ME, Postma JP, Groendijk H, Kalk KH, Hol WG, Opperdoes FR, Proteins. 1991;10(1):33-49. PMID:2062827
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