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Thermodynamic and Structural Adaptation Differences between the Mesophilic and Psychrophilic Lactate Dehydrogenases
- Source :
- Biochemistry. 56:3587-3595
- Publication Year :
- 2017
- Publisher :
- American Chemical Society (ACS), 2017.
-
Abstract
- 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.
- Subjects :
- 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
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 56
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....909acf5b616fb0ddd1c5316b83f53e5a