用^211At和^131I标记蛋白质的研究

报道了砹—211和碘—131标记蛋白质的方法.通过过氧化氢或氯胺T直接氧化制备,使用凝胶色谱从反应产物中分离标记蛋白质,相对法比较放射性计数测定标记产率,过氧化氢适用于~(211)At标记蛋白质,氯胺T有利于~(131)I标记蛋白质.8次实验的结果表明,用过氧化氢氧化标记的~(211)At牛血清白蛋白产率96.4％,氯胺T氧化标记的~(?)I牛血清白蛋白产率66.1％.间接法标记蛋白质,放射性核素~(211)At同对氨基苯甲酸反应获得对—~(211)At—苯甲酸,经乙醚萃取和高效液体色谱分离,然后再偶联到免疫球蛋白或牛血清白蛋白上。动物实验结果表明,此种结合的标记蛋白质在体内稳定,标记率不低于初始~(211)At放射性活度的40%.

STUDIES ON THE LABELLING OF PROTEINS WITH ~(211)At AND ~(131)I

211At or 131I labelled proteins have been prepared by direct oxidation with hydrogen peroxide or chloramine-T. Sephadex chromatographic column was used to separate labelled proteins from reactive products and the labelling yield was determined by the relative method comparing radioactive counts. The labelling of proteins with 211At is favourable under the condition of hydrogen peroxide, but the labelling of proteins with 131I is favourable under the oxidant chloramine-T. The results of eight .different experiments show that the yield of 211At-BSA labelled by oxidation of hydrogen peroxide can be high up to 96.4% and the yield of 131I-BSA labelled by oxidation of chloramine-T 66.1%.As an indirect method for the labelling of proteins, an organic compound was labelled by radio-astatine or radio-iodine and then the compound was conjugated to proteins. The nuclide 211At reacted with diazo-compound of para-amino-benzoic acid to obtaine para-astato-benzoic acid. The labelled compound was separated by ether extraction and high performance liquid chromatography, and then it is conjugated with IgG or BSA by a mixed anhydride reaction. The animal experiments show that the conjugate is stable in vivo and contains at least 40% of initial activity of 211At.