Details

Autor(en) / Beteiligte

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

Titel

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

Ist Teil von

• Journal of bioenergetics and biomembranes, 2020-04, Vol.52 (2), p.61-70

Ort / Verlag

New York: Springer US

Erscheinungsjahr

2020

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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; K D 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 TΔS b 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 (T m ) 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.