Abstract: PRELIMINARY STUDY ON RARE EARTH BOUND PROTEINS IN NATURAL PLANT FERN DICRANOPTERES DICHOTOMAGuo Fanqing;Wang Yuqi;Sun Jingxin;Chen Hongmin（Institute of High Energy Physics,Laboratory of Nuclear Analysis Techniques,the Chinese Academy of Sciences,P.O.Box 2732,Beijing 100080）Xu Lei;Cao Guoying（Graduate School of the Chinese Academy of Agriculture,Beijing 100081）Abstract:biochemical techniques,including pH variation ,outsalting,ultracentrifugation,gel filtration chromatography and electrophoresis,together with instrumental neutron activation analysis（INAA）have been employed to study the rare earth elements(REE）bound proteins in the natural plant fern, Dicranopteris dichotoma.INAA is also used to identify whether the proteins are bound firmly with REE. The results obtained preliminarily show that two REE bound proteins（RBP-Ⅰand RBP-Ⅱ）have been separated．The molecular weight of RBP-Ⅰon Sephadex G-200 gel column is about 8×105 and that of RBP-Ⅱis less than 12400,respectively.However, SDS－PAGE of the two proteins shows that they mainly have two protein subunits with M＝14 100 and 38 700．They are probably conjugated proteins,the glycoproteins with different glyco－units.Keywords:REE bound protein MAA NAA biochemical techniques Dicranopteris dichotoma