Iodination of Ricin D |
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Authors: | Masatsune Ishiguro Etsuko Taira Kazuto Mashima Gunki Funatsu Masaru Funatsu Motosuke Kikutani |
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Affiliation: | 1. Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812;2. Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki 852 |
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Abstract: | Approximately five tyrosine residues of ricin D were iodinated preferentially under appropriate conditions probably forming diiodotyrosine. Iodination of this toxin carried out in 0.1 m phosphate buffer at pH 7.0 and 0°C for 60 min with a 20 fold molar excess of iodine per mole of protein, yielded a main component which appeared as a single band on polyacrylamide gel disc electrophoresis. Analysis of protein-bound radioactivity and the content of diiodotyrosine of 181I-labeled ricin D revealed that two tyrosine residues in the isoleucyl chain and three in the alanyl chain were substituted. The toxicity of iodinated ricin D decreased to one hundredth of that of native protein, However, the hemagglutinating activity of this protein was not affected by the iodination reaction. |
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Keywords: | family-19 chitinase chitin-binding domain protoplast |
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