Importance of Aspartate Residues in Balancing the Flexibility and Fine-Tuning the Catalysis of Human 3-Phosphoglycerate Kinase
| Autor: | Éva Gráczer, Péter Závodszky, Andrea Varga, Zoltán Gugolya, Ferenc Vonderviszt, Mária Vas, Zoltan Palmai, Erika Balog |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Alanine
chemistry.chemical_classification Aspartic Acid biology Protein Conformation Stereochemistry Kinase Mutant Active site Biochemistry Catalysis Adenosine Diphosphate Phosphoglycerate Kinase Adenosine Triphosphate Protein structure Enzyme chemistry biology.protein Humans Thermodynamics Magnesium Nucleotide |
| Zdroj: | Biochemistry. 51:10197-10207 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | The exact role of the metal ion, usually Mg(2+), in the catalysis of human 3-phosphoglycerate kinase, a well-studied two-domain enzyme, has not been clarified. Here we have prepared single and double alanine mutants of the potential metal-binding residues, D374 and D218. While all mutations weaken the catalytic interactions with Mg(2+), they surprisingly strengthen binding of both MgADP and MgATP, and the effects are even more pronounced for ADP and ATP. Thermodynamic parameters of binding indicate an increase in the binding entropy as a reason for the strengthening. In agreement with the experimental results, computer-simulated annealing calculations for the complexes of these mutants have supported the mobility of the nucleotide phosphates and, as a consequence, formation of their new interaction(s) within the active site. A similar type of mobility is suggested to be a characteristic feature of the nucleotide site of the wild-type enzyme, too, both in its inactive open conformation and in the active closed conformation. This mobility of the nucleotide phosphates that is regulated by the aspartate side chains of D218 and D374 through the complexing Mg(2+) is suggested to be essential in enzyme function. |
| Databáze: | OpenAIRE |
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