Among the functions exerted by eukaryotic lactate dehydrogenases, it is of importance the generation of lactate in muscles subjected to fatigue or to limited oxygen availability, with both these conditions triggering a decrease of cellular pH. However, the mutual dependence between lactate dehydrogenase (LDH) catalytic action and lactic acidosis is far from being fully understood. Here we show that the tetrameric LDH from rabbit skeletal muscle undergoes allosteric transitions as a function of pH, i.e. the enzyme obeys Michaelis-Menten kinetics at neutral or slightly alkaline pH values, and features sigmoidal kinetics at pH 6.5 or lower. Remarkably, we also report that a significant dissociation of tetrameric rabbit LDH occurs under acidic conditions, with pyruvate/NAD+ or citrate counteracting this effect. Moreover, citrate strongly activates rabbit LDH, inducing the enzyme to feature Michaelis-Menten kinetics. Further, using primary rabbit skeletal muscle cells we tested the generation of lactate as a function of pH, and we detected a parallel decrease of cytosolic pH and secretion of lactate. Overall, our observations indicate that lactic acidosis is antagonized by LDH dissociation, the occurrence of which is regulated by citrate and by allosteric transitions of the enzyme induced by pyruvate.
Iacovino L.G., Rossi M., Di Stefano G., Rossi V., Binda C., Brigotti M., et al. (2022). Allosteric transitions of rabbit skeletal muscle lactate dehydrogenase induced by pH-dependent dissociation of the tetrameric enzyme. BIOCHIMIE, 199, 23-35 [10.1016/j.biochi.2022.03.008].
Allosteric transitions of rabbit skeletal muscle lactate dehydrogenase induced by pH-dependent dissociation of the tetrameric enzyme
Di Stefano G.Membro del Collaboration Group
;Rossi V.Membro del Collaboration Group
;Binda C.Membro del Collaboration Group
;Brigotti M.Membro del Collaboration Group
;Cerini S.Membro del Collaboration Group
;Hochkoeppler A.
2022
Abstract
Among the functions exerted by eukaryotic lactate dehydrogenases, it is of importance the generation of lactate in muscles subjected to fatigue or to limited oxygen availability, with both these conditions triggering a decrease of cellular pH. However, the mutual dependence between lactate dehydrogenase (LDH) catalytic action and lactic acidosis is far from being fully understood. Here we show that the tetrameric LDH from rabbit skeletal muscle undergoes allosteric transitions as a function of pH, i.e. the enzyme obeys Michaelis-Menten kinetics at neutral or slightly alkaline pH values, and features sigmoidal kinetics at pH 6.5 or lower. Remarkably, we also report that a significant dissociation of tetrameric rabbit LDH occurs under acidic conditions, with pyruvate/NAD+ or citrate counteracting this effect. Moreover, citrate strongly activates rabbit LDH, inducing the enzyme to feature Michaelis-Menten kinetics. Further, using primary rabbit skeletal muscle cells we tested the generation of lactate as a function of pH, and we detected a parallel decrease of cytosolic pH and secretion of lactate. Overall, our observations indicate that lactic acidosis is antagonized by LDH dissociation, the occurrence of which is regulated by citrate and by allosteric transitions of the enzyme induced by pyruvate.File | Dimensione | Formato | |
---|---|---|---|
Allosteric_compressed(1).pdf
Open Access dal 01/09/2023
Descrizione: Accepted Manuscript
Tipo:
Postprint
Licenza:
Licenza per Accesso Aperto. Creative Commons Attribuzione - Non commerciale - Non opere derivate (CCBYNCND)
Dimensione
686.21 kB
Formato
Adobe PDF
|
686.21 kB | Adobe PDF | Visualizza/Apri |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.