Thermodynamic and Structural Adaptation Differences between the Mesophilic and Psychrophilic Lactate Dehydrogenases
| العنوان: | Thermodynamic and Structural Adaptation Differences between the Mesophilic and Psychrophilic Lactate Dehydrogenases |
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| المؤلفون: | Sergei Khrapunov, Robert Callender, Eric C. Chang |
| المصدر: | Biochemistry. 56:3587-3595 |
| بيانات النشر: | American Chemical Society (ACS), 2017. |
| سنة النشر: | 2017 |
| مصطلحات موضوعية: | 0301 basic medicine, Protein Denaturation, Protein Conformation, Swine, Biochemistry, Article, Substrate Specificity, Methylamines, 03 medical and health sciences, chemistry.chemical_compound, Lactate dehydrogenase, Enzyme Stability, Animals, Glycolysis, Psychrophile, chemistry.chemical_classification, L-Lactate Dehydrogenase, 030102 biochemistry & molecular biology, biology, Active site, NAD, Adaptation, Physiological, Perciformes, 030104 developmental biology, Enzyme, chemistry, Osmolyte, biology.protein, Thermodynamics, Lactate dehydrogenases, Mesophile |
| الوصف: | The thermodynamics of substrate binding and enzymatic activity of a glycolytic enzyme, lactate dehydrogenase (LDH), from both porcine heart, phLDH (Sus scrofa; a mesophile), and mackerel icefish, cgLDH (Chamapsocephalus gunnari; a psychrophile), were investigated. Using a novel and quite sensitive fluorescence assay that can distinguish protein conformational changes close to and distal from the substrate binding pocket, a reversible global protein structural transition preceding the high-temperature transition (denaturation) was surprisingly found to coincide with a marked change in enzymatic activity for both LDHs. A similar reversible structural transition of the active site structure was observed for phLDH but not for cgLDH. An observed lower substrate binding affinity for cgLDH compared to that for phLDH was accompanied by a larger contribution of entropy to ΔG, which reflects a higher functional plasticity of the psychrophilic cgLDH compared to that of the mesophilic phLDH. The natural osmolyte, trimethylamine N-oxide (TMAO), increases stability and shifts all structural transitions to higher temperatures for both orthologs while simultaneously reducing catalytic activity. The presence of TMAO causes cgLDH to adopt catalytic parameters like those of phLDH in the absence of the osmolyte. Our results are most naturally understood within a model of enzyme dynamics whereby different conformations of the enzyme that have varied catalytic parameters (i.e., binding and catalytic proclivity) and whose population profiles are temperature-dependent and influenced by osmolytes interconvert among themselves. Our results also show that adaptation can be achieved by means other than gene mutations and complements the synchronic evolution of the cellular milieu. |
| تدمد: | 1520-4995 0006-2960 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::909acf5b616fb0ddd1c5316b83f53e5aTest https://doi.org/10.1021/acs.biochem.7b00156Test |
| حقوق: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....909acf5b616fb0ddd1c5316b83f53e5a |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15204995 00062960 |
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