Details

Autor(en) / Beteiligte

• Muñoz‐Bacasehua, César
• Rosas‐Rodríguez, Jesús A.
• López‐Zavala, Alexis Alonso
• Valenzuela‐Soto, Elisa M.

Titel

Spectroscopic analysis of coenzyme binding to betaine aldehyde dehydrogenase dependent on potassium

Ist Teil von

• Luminescence (Chichester, England), 2021-11, Vol.36 (7), p.1733-1742

Ort / Verlag

Bognor Regis: Wiley Subscription Services, Inc

Erscheinungsjahr

2021

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Glycine betaine is the main osmolyte synthesized and accumulated in mammalian renal cells. Glycine betaine synthesis is catalyzed by the enzyme betaine aldehyde dehydrogenase (BADH) using NAD+ as the coenzyme. Previous studies have shown that porcine kidney betaine aldehyde dehydrogenase (pkBADH) binds NAD+ with different affinities at each active site and that the binding is K+ dependent. The objective of this work was to analyze the changes in the pkBADH secondary and tertiary structure resulting from variable concentrations of NAD+ and the role played by K+. Intrinsic fluorescence studies were carried out at fixed‐variable concentrations of K+ and titrating the enzyme with varying concentrations of NAD+. Fluorescence analysis showed a shift of the maximum emission towards red as the concentration of K+ was increased. Changes in the exposure of tryptophan located near the NAD+ binding site were found when the enzyme was titrated with NAD+ in the presence of potassium. Fluorescence data analysis showed that the K+ presence promoted static quenching that facilitated the pkBADH–NAD+ complex formation. DC data analysis showed that binding of K+ to the enzyme caused changes in the α‐helix content of 4% and 12% in the presence of 25 mM and 100 mM K+, respectively. The presence of K+ during NAD+ binding to pkBADH increased the thermal stability of the complex. These results indicated that K+ facilitated the pkBADH–NAD+ complex formation and suggested that K+ caused small changes in secondary and tertiary structures that could influence the active site conformation. Potassium caused changes in the exposure tryptophans located near the NAD+ binding site when the enzyme was titrated with NAD+. Potassium presence promoted static quenching that facilitated pkBADH–NAD+ complex formation. Potassium presence during NAD+ binding caused changes in the pkBADH α‐helix content and increased complex thermal stability.