The effects of chemical and radioactive properties of Tl-201 on human erythrocyte glucose 6-phosphate dehydrogenase activity
Received 16 April 2009; received in revised form 1 November 2009; accepted 23 November 2009. published online 11 February 2010.
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.
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