Possible inhibition mechanism of dobutamine hydrochloride as potent inhibitor for human glucose-6-phosphate dehydrogenase enzyme

Abstract

Glucose-6-phosphate dehydrogenase (G6PD) is the first rate-limiting enzyme in the pentose phosphate pathway. One of the enzyme’s most important functions is the production of a reducing agent that is essential for preserving the level of reduced glutathione (GSH). However, some chemicals, such as industrial waste and the active ingredients of several drugs, can cause reduction or blockage in this enzyme’s activity. This case causes the occurrence of anemia by damaging erythrocytes. In this study, the G6PD enzyme was purified 21,981 fold with affinity chromatography and the effects of the active ingredients of some antiarrhythmic drugs on enzyme activity were investigated with in vitro and in silico methods. We found that dobutamine hydrochloride significantly decreased enzyme activity and its inhibitory constant (K_i) value was calculated as 19.02 ± 4.83 mM. The in vitro study results also show that dobutamine hydrochloride is a potent inhibitor of enzyme activity. We also found that dobutamine hydrochloride inhibits the hG6PD enzyme’s activity by causing structural alterations in substrate and coenzyme binding sites.

Communicated by Ramaswamy H. Sarma

Keywords:

• Antiarrhythmic drugs
• glucose-6-phosphate dehydrogenase
• allosteric modulation
• in vitro
• in silico

Acknowledgements

The authors express their thanks to the Scientific Research Unit of Kilis 7 Aralik University for its financial support and to Dr. Halide Sedef Karaman for contributing the docking study process of this article, as well as to Dr. Bekir Bulent Arpaci for providing the equipment needed to carry out this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Equations

(I) $\text{EU}=\frac{{\Delta }_{\lambda 340}}{\epsilon \times t\times l}\times \frac{V_E}{V_T}\times \text{DF}$ ε: The extinction coefficient of NADPH, 6.22 mM⁻¹cm⁻¹; t: Time of reaction, minute; l: Beam path, cm; V_E: Total enzyme volume; V_T: Total cuvette volume; DF: Dilution factor

(II) $V_{\max }^I=\frac{V_{\max }}{1+\raisebox{1ex}{$[I]$}\!\left/ \!\raisebox{-1ex}{$K_i$}\right.}$ V_max^I The reaction rate when the enzyme is fully saturated by substrate presences of inhibitor; V _max: The reaction rate when the enzyme is fully saturated by substrate; [I]: Inhibitor concentration; K_i: Binding affinity of inhibitor to the enzyme

Additional information

Funding

This study was financed by the Scientific Research Unit of Kilis 7 Aralik University (Grant Number: 12432LTP).