Homocysteine effects on cellular glutathione peroxidase (GPx-1) activity under in vitro conditions

Abstract

Hyperhomocysteinemia is associated with a lot of diseases including cardiovascular diseases and neural tube defect, but it has not been clarified exactly which mechanism is responsible for occurence disease. Here, homocysteine (Hcy) and cysteine (Cys), which are thiol containing amino acids, were examined for their effect on glutathione peroxidase (GPx) activity. İt was observed that the GPx-1 activity was inhibited under severe hyperhomocysteinemia (50–500 μM Hcy) conditions, especially at low glutathione concentrations but that cysteine increased GPx-1 activity at low glutathione concentrations and inhibition clearly appeared at 500 μM Cys concentration.

Keywords::

• Glutathione peroxidase
• homocysteine
• cysteine
• glutathione reductase

Acknowledgements

The authors wish to thank Dr. Atilla Dikmen and Dr. Şeref Erdoğan for their expert opinions. This project was supported by Çukurova University Research Foundation (2003YL7).