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| {{STRUCTURE_2ldb| PDB=2ldb | SCENE= }} | | {{STRUCTURE_2ldb| PDB=2ldb | SCENE= }} |
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| '''STRUCTURE DETERMINATION AND REFINEMENT OF BACILLUS STEAROTHERMOPHILUS LACTATE DEHYDROGENASE'''
| | ===STRUCTURE DETERMINATION AND REFINEMENT OF BACILLUS STEAROTHERMOPHILUS LACTATE DEHYDROGENASE=== |
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| ==Overview==
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| Structures have been determined of Bacillus stearothermophilus "apo" and holo lactate dehydrogenase. The holo-enzyme had been co-crystallized with the activator fructose 1,6-bisphosphate. The "apo" lactate dehydrogenase structure was solved by use of the known apo-M4 dogfish lactate dehydrogenase molecule as a starting model. Phases were refined and extended from 4 A to 3 A resolution by means of the noncrystallographic molecular 222 symmetry. The R-factor was reduced to 28.7%, using 2.8 A resolution data, in a restrained least-squares refinement in which the molecular symmetry was imposed as a constraint. A low occupancy of coenzyme was found in each of the four subunits of the "apo"-enzyme. Further refinement proceeded with the isomorphous holo-enzyme from Bacillus stearothermophilus. After removing the noncrystallographic constraints, the R-factor dropped from 30.3% to a final value of 26.0% with a 0.019 A and 1.7 degrees r.m.s. deviation from idealized bond lengths and angles, respectively. Two sulfate ions per subunit were included in the final model of the "apo"-form--one at the substrate binding site and one close to the molecular P-axis near the location of the fructose 1,6-bisphosphate activator. The final model of the holo-enzyme incorporated two sulfate ions per subunit, one at the substrate binding site and another close to the R-axis. One nicotinamide adenine dinucleotide coenzyme molecule per subunit and two fructose 1,6-bisphosphate molecules per tetramer were also included. The phosphate positions of fructose 1,6-bisphosphate are close to the sulfate ion near the P-axis in the "apo" model. This structure represents the first reported refined model of an allosteric activated lactate dehydrogenase. The structure of the activated holo-enzyme showed far greater similarity to the ternary complex of dogfish M4 lactate dehydrogenase with nicotinamide adenine dinucleotide and oxamate than to apo-M4 dogfish lactate dehydrogenase. The conformations of nicotinamide adenine dinucleotide and fructose 1,6-bisphosphate were also analyzed.
| | The line below this paragraph, {{ABSTRACT_PUBMED_2330370}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 2330370 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_2330370}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Piontek, K.]] | | [[Category: Piontek, K.]] |
| [[Category: Rossmann, M G.]] | | [[Category: Rossmann, M G.]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 09:29:50 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:19:32 2008'' |
