PURIFICATION OF THE BRAIN HORMONE OF THE SILKWORM BOMBYX MORI

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Abstract
The Bombyx brain hormone was purified by use of the heating, ammonium sulfate precipitation, Sephadex gel-filtration, and DEAE-cellulose chromatography. On the basis of protein measurement, about 8000-fold purification was achieved. The most purified preparation was active by 0.002 [mu]g protein when injected into brainless pupae of Samia cynthia ricini, but the data suggested that it was not satisfactorily pure yet. The hormone manifested highly heterogenous molecular forms which were revealed by Sephadex gel-filtration and by DEAE-cellulose chromatography. The molecular weights of the major components were estimated by Sephadex gel-filtration as ranging from 9,000 to 31,000.