Role of potassium levels in pkBADH heterogeneity of NAD+ binding site

César Muñoz-Bacasehua, Jesus A. Rosas-Rodríguez, Aldo A. Arvizu-Flores, Elisa M. Valenzuela-Soto*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Betaine aldehyde dehydrogenase (BADH) catalyzes the oxidation of betaine aldehyde to glycine betaine using NAD+ as a coenzyme. Studies in porcine kidney BADH (pkBADH) suggested that the enzyme exhibits heterogeneity of active sites and undergoes potassium-induced conformational changes. This study aimed to analyze if potassium concentration plays a role in the heterogeneity of pkBADH active sites through changes in NAD+ affinity constants, in its secondary structure content and stability. The enzyme was titrated with NAD+ 1 mM at fixed-variable KCl concentration, and the interaction measured by Isothermal Titration Calorimetry (ITC) and Circular Dichroism (CD). ITC data showed that K+ increased the first active site affinity in a manner dependent on its concentration; KD values to the first site were 14.4, 13.1, and 10.4 μM, at 25, 50, and 75 mM KCl. ΔG values showed that the coenzyme binding is a spontaneous reaction without changes between active sites or depending on KCl concentration. ΔH and TΔSb values showed that NAD+ binding to the active site is an endothermic process and is carried out at the expense of changes in entropy. α-Helix content increased as KCl increased, enzyme (Tm)app values were 2.6 °C and 3.3 °C higher at 20 mM and 200 mM K+. PkBADH molecular model showed three different interaction K+ sites. Results suggested K+ can interact with pkBADH and cause changes in the secondary structure, it provokes changes in the enzyme affinity by the coenzyme, and in the thermostability.

Original languageEnglish
Pages (from-to)61-70
Number of pages10
JournalJournal of Bioenergetics and Biomembranes
Issue number2
StatePublished - 1 Apr 2020

Bibliographical note

Funding Information:
César Muñoz-Bacasehua gratefully acknowledges a scholarship from CONACyT for graduate studies. Authors are grateful to Dr. G. Garza-Ramos for providing facilities and constant support to carry out CD spectra.

Publisher Copyright:
© 2020, Springer Science+Business Media, LLC, part of Springer Nature.


  • Active site reactivity
  • Betaine aldehyde dehydrogenase
  • Conformational changes
  • Glycine betaine
  • Molecular characterization


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