Study on labelling conditions of 125I-SOD chloramine T method and Iodogen method

The five factors (i.e. labelling temperature, chloramine T quantity, labelling reaction time, concentration and volume of PB buffer solution) effecting the labelling of 125I-SOD chloramine T method were studied by an orthogonal experimental table. Each factor had four kinds of level. The labelled product was separated by chromatographic column Sephadex G25, then the labelling rate and relative activity were determined. An experiment of sixteen groups was enough for obtaining optimal labelling conditions. On the basis of study on chloramine T method, the three factors (i.e. labelling temperature, Iodogen quantity and reaction time) effecting the labelling of 125I-SOD Iodogen method were also completed by another orthogonal experimental table, and three kinds of label were adopted for each factor. The optimal conditions were reached after nine groups of experiment have been completed. The final results showed that when the labelling temperature was 15 deg C and reaction time was 15 minutes, for 20 μg SOD the Iodogen was 50 μg, and the labelling rate was 79.0%, 125I-SOD relative activity was 98.2%, radiochemical purity of 125I-SOD was 95.7%, specific radioactivity was 2.92 x 105 Bq'μg. The Iodogen method is much better than chloramine T method