鎘處理百日草內鎘結合多胜肽

Cadmium-Binding Polypeptides in Cadmium-Treated Zinnia

五週大的百日草幼苗，以水耕法施以10µM鎘濃度的先處理一週後，移植於含45µM鎘的營養液下處理。在不同的處理時間下，分別收集經前處理及單一的45µM處理的植株進行測試。在高效能液態色層分析圖譜的比較下，有經先處理的植株含較多的氫硫化合物及麩胱甘太，而且在七個波峰的氫硫化合物中的第三和第四波峰在處理24小時內遞增至最高，隨後而遞減，在96小時時恢復原來的濃度。進一步分離與鑑定低分子與高分子複合物所用的材料都用先處理者。植物的萃取液經DE 52的離子交換和Sephadex-50膠體過濾柱型色層分析，取得的兩個層析分別是高分子與低分子鎘結合復合物。低分子鎘結合復合物在高效能液態色層分析圖譜中顯示兩個波峰，氨基酸分析儀鑑定兩著所占有的組氨酸量高達90%以上，且其滯留時間比麩胱甘太短。高分子鎘結合複合物則顯示有七個波峰，除第一波峰含有的組氨酸高達85%外，其餘波峰所含的組氨酸都在0.1 %以下，植物螯合物中麩氨酸/甘氨酸的比例分別為3和4。

Five-week-old seedlings of Zinnia elegans were hydroponically cultured in Hoagland's solution containing 45 µM Cd2+ with or without one week of prior exposure to 10 µM Cd2+. Profiles of HPLC indicated that plants previously exposed to 10 µM Cd2+ developed more sulfurhydryl groups and glutathione than plants not exposed to that prior treatment. Individual peaks of sulfurhydryl groups displayed a prominent increase at 24 h, following by a gradual decrease to initial levels of sulfurhydryl after 96 h. Further isolation and purification of metal-binding complexes was done using DE 52, Sephadex, and HPLC chromatographic separations. Two fractions of the LMW complex contained more than 90% of the histidine-like substance in total amino acids. The HMW complex had five peaks in the HPLC profile. One major peak contained more than 85% of the histidine-like substance, whereas other peaks contained less than 0.1% of the histidine, along with phytochelatins with n number 3 and 4.