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目的为提高人重组粒细胞集落刺激因子（ｈｕｍａｎｒｅｃｏｍｂｉｎａｎｔｇｒａｎｕｌｏｃｙｔｅｃｏｌｏｎｙ－ｓｔｉｍｕｌａｔｉｎｇｆａｃｔｏｒ，ｒｈＧ－ＣＳＦ）的稳定性和活性，对ｒｈＧ－ＣＳＦ进行改造和体内、外活性研究。方法利用定向点突变技术，将人重组粒细胞集落刺激因子第１７位游离的半胱氨酸编码序列突变为丙氨酸序列，ＤＮＡ序列分析证明后，在大肠杆菌中表达突变蛋白。利用Ｇ－ＣＳＦ依赖细胞株ＮＦＳ－６０，对在不同温度及在人血浆中保存的Ｇ－ＣＳＦ蛋白（Ｇ－ＣＳＦ－Ａｌａ１７）和野生型的Ｇ－ＣＳＦ进行活性测定。腹腔注射后小鼠外周血白细胞计数检测其体内生物学活性。结果ＤＮＡ序列分析表明１７位半胱氨酸突变为丙氨酸，并在大肠杆菌中表达成功Ｇ－ＣＳＦ－Ａｌａ１７。纯化的突变蛋白对ＮＦＳ－６０细胞具有刺激活性；与野生型Ｇ－ＣＳＦ相比，在各种温度储存的突变蛋白保留更高的活性，与人血浆孵育５０小时后突变蛋白仍保持活性；小鼠一次性体内注射突变蛋白后外周血白细胞数明显高于野生型Ｇ－ＣＳＦ。结论Ｇ－ＣＳＦ突变体（Ｇ－ＣＳＦ－Ａｌａ１７）较野生型的Ｇ－ＣＳＦ具有更高的体外稳定性和体内造血刺激活性。
Objective To improve the stability and activity of human recombinant human granulocyte colony-stimulating factor (rhG-CSF), and to study rhG-CSF transformation and in vitro and in vivo activity. Methods The cysteine coding sequence of human recombinant human granulocyte colony stimulating factor 17 was mutated to alanine using directional point mutation technique. After DNA sequence analysis proved, the mutant protein was expressed in E. coli. The G-CSF protein (G-CSF-Ala17) and wild-type G-CSF stored at different temperatures and in human plasma were assayed for activity using the G-CSF dependent cell line NFS-60. Peritoneal injection of peripheral blood leukocytes in mice to detect the biological activity. Results DNA sequence analysis revealed a mutation of cysteine 17 to alanine and the successful expression of G-CSF-Ala17 in E. coli. Purified muteins have stimulatory activity on NFS-60 cells; muteins stored at various temperatures retain higher activity compared to wild-type G-CSF and muteins remain active after incubation with human plasma for 50 hours; After a one-time in vivo injection of mutein in mice, the number of peripheral leukocytes was significantly higher than that of wild-type G-CSF. Conclusion G-CSF mutant (G-CSF-Ala17) has higher in vitro stability and in vivo hematopoietic stimulating activity than wild-type G-CSF.