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| {{STRUCTURE_2zf5| PDB=2zf5 | SCENE= }} | | {{STRUCTURE_2zf5| PDB=2zf5 | SCENE= }} |
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| '''Crystal Structure of highly thermostable glycerol kinase from a hyperthermophilic archaeon'''
| | ===Crystal Structure of highly thermostable glycerol kinase from a hyperthermophilic archaeon=== |
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| ==Overview==
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| The crystal structure of glycerol kinase from the hyperthermophilic archaeon Thermococcus kodakaraensis (Tk-GK) in a dimeric form was determined at a resolution of 2.4 A. This is the first crystal structure of a hyperthermophilic glycerol kinase. The overall structure of the Tk-GK dimer is very similar to that of the Escherichia coli glycerol kinase (Ec-GK) dimer. However, two dimers of Ec-GK can associate into a tetramer with a twofold axis, whereas those of Tk-GK cannot. This may be the reason why Tk-GK is not inhibited by fructose 1,6-bisphosphate, because the fructose 1,6-bisphosphate binding site is produced only when a tetrameric structure is formed. Differential scanning calorimetry analyses indicate that Tk-GK is a highly thermostable protein with a melting temperature (T(m)) of 105.4 degrees C for the major transition. This value is higher than that of Ec-GK by 34.1 degrees C. Comparison of the crystal structures of Tk-GK and Ec-GK indicate that there is a marked difference in the number of ion pairs in the alpha16 helix. Four ion pairs, termed IP1-IP4, are formed in this helix in the Tk-GK structure. To examine whether these ion pairs contribute to the stabilization of Tk-GK, four Tk-GK and four Ec-GK derivatives with reciprocal mutations at the IP1-IP4 sites were constructed. The determination of their stabilities indicates that the removal of each ion pair does not affect the stability of Tk-GK significantly, whereas the mutations designed to introduce one of these ion pairs stabilize or destabilize Ec-GK considerably. These results suggest that the ion pairs in the alpha16 helix contribute to the stabilization of Tk-GK in a cooperative manner. | | The line below this paragraph, {{ABSTRACT_PUBMED_18422647}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 18422647 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_18422647}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Nucleotide-binding]] | | [[Category: Nucleotide-binding]] |
| [[Category: Transferase]] | | [[Category: Transferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed May 7 08:51:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:55:09 2008'' |
