4ake
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(New page: 200px<br /><applet load="4ake" size="450" color="white" frame="true" align="right" spinBox="true" caption="4ake, resolution 2.2Å" /> '''ADENYLATE KINASE'''<b...)
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Revision as of 17:17, 20 November 2007
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ADENYLATE KINASE
Overview
BACKGROUND: Adenylate kinases undergo large conformational changes during, their catalytic cycle. Because these changes have been studied by, comparison of structures from different species, which share approximately, one-third of their residues, only rough descriptions have been possible to, date. RESULTS: We have solved the structure of unligated adenylate kinase, from Escherichia coli at 2.2 degree resolution and compared it with the, high-resolution structure of the same enzyme ligated with an inhibitor, mimicking both substrates, ATP and AMP. This comparison shows that, upon, substrate binding, the enzyme increases its chain mobility in a region, remote from the active center. As this region 'solidifies' again on, substrate release, we propose that it serves as a 'counterweight', balancing the substrate binding energy. CONCLUSION: The comparison of two, very different conformations of the same polypeptide chain revealed, kinematic details of the catalytic cycle. Moreover, it indicated that, there exists an energetic counterweight compensating the substrate binding, energy required for specificity. This counterweight prevents the enzyme, from dropping into a rate-reducing energy well along the reaction, coordinate.
About this Structure
4AKE is a Single protein structure of sequence from Escherichia coli. Active as Adenylate kinase, with EC number 2.7.4.3 Full crystallographic information is available from OCA.
Reference
Adenylate kinase motions during catalysis: an energetic counterweight balancing substrate binding., Muller CW, Schlauderer GJ, Reinstein J, Schulz GE, Structure. 1996 Feb 15;4(2):147-56. PMID:8805521
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