The effects of chemical and radioactive properties of Tl-201 on human erythrocyte glucose 6-phosphate dehydrogenase activity

Abstract 

Aim

The inhibitory effects of thallium-201 (²⁰¹Tl) solution on human erythrocyte glucose 6-phosphate dehydrogenase (G6PD) activity were investigated.

Methods

For this purpose, erythrocyte G6PD was initially purified 835-fold at a yield of 41.7% using 2′,5′-Adenosine diphosphate sepharose 4B affinity gel chromatography. The purification was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which showed a single band for the final enzyme preparation. The in vitro and in vivo effects of the ²⁰¹Tl solution including Tl⁺, Fe⁺³ and Cu⁺² metals and the in vitro effects of the radiation effect of the ²⁰¹Tl solution and non-radioactive Tl⁺, Fe⁺³ and Cu⁺² metals on human erythrocyte G6PD enzyme were studied. Enzyme activity was determined with the Beutler method at 340 nm using a spectrophotometer. All purification procedures were carried out at +4°C.

Results

²⁰¹Tl solution and radiation exposure had inhibitory effects on the enzyme activity. IC₅₀ value of ²⁰¹Tl solution was 36.86 μl ([Tl⁺]: 0.0036 μM, [Cu⁺²]: 0.0116 μM, [Fe⁺³]: 0.0132 μM), of human erythrocytes G6PD. Seven human patients were also used for in vivo studies of ²⁰¹Tl solution. Furthermore, non-radioactive Tl⁺, Fe⁺³ and Cu⁺² were found not to have influenced the enzyme in vitro.

Conclusion

Human erythrocyte G6PD activity was inhibited by exposure for up to 10 minutes to 0.057 mCi/kg ²⁰¹Tl solution. It was detected in in vitro and in vivo studies that the human erythrocyte G6PD enzyme is inhibited due to the radiation effect of ²⁰¹Tl solution.

Keywords: Glucose 6-phosphate dehydrogenase, Radiation, Inhibition