目的可致肿瘤细胞死亡的人α乳清蛋白(human alpha-lactalbumin made lethal to tumor cells,HAMLET)是一种可导致多种癌细胞死亡的强效选择性肿瘤杀伤蛋白质-脂酸复合物。为了使HAMLET应用于肿瘤的治疗并对其杀伤机制进行探讨,我们需...目的可致肿瘤细胞死亡的人α乳清蛋白(human alpha-lactalbumin made lethal to tumor cells,HAMLET)是一种可导致多种癌细胞死亡的强效选择性肿瘤杀伤蛋白质-脂酸复合物。为了使HAMLET应用于肿瘤的治疗并对其杀伤机制进行探讨,我们需要建立和优化简便、快速、规模化制备与纯化HAMLET的方法。方法通过构建人α乳清蛋白分泌型细胞MCF-7的cDNA文库,PCR扩增出编码人α乳清蛋白成熟肽段的全长序列,然后克隆入pET30a(+)表达载体质粒,并转化BL21(DE3)宿主大肠杆菌。经过IPTG诱导,表达细菌的裂解,蛋白体外复性,Ni-NTA亲和层析柱纯化等步骤,获得了高纯度的重组人α乳清蛋白的C端His标签融合蛋白。纯化蛋白经EDTA脱钙后,与油酸(oleic acid,OA)在加热条件下制备HAMLET复合物。同时,对HAMLET的理化特性和生物学活性进行检测。结果通过与经典方法制备的牛α乳清蛋白和OA复合物(BAMLET)进行比较,发现我们制备的HAMLET在紫外吸收光谱、疏水性质特征及肿瘤杀伤活力方面与BAMLET活性相符,并且可引起HeLa肿瘤细胞的凋亡样程序性死亡。结论本研究自主制备的HAMLET成本经济、方法简便且具有较好的规模化放大前景,为日后临床应用奠定基础。展开更多
In order to establish a possible evolutionary correlation between α lactalbumin and lysozyme,site\|directed mutagenesis on α\|lactalbumin cDNA was performed to change α\|lactalbumin into lysozyme.The gene of α\|la...In order to establish a possible evolutionary correlation between α lactalbumin and lysozyme,site\|directed mutagenesis on α\|lactalbumin cDNA was performed to change α\|lactalbumin into lysozyme.The gene of α\|lactalbumin was cloned into phagemid pSK +vector and the single strand template of which was prepared.Thereafter,the mutagenic oligonucleotide primers were designed and used to synthesize the mutated double strand DNA.By means of this site\|directed mutagenesis,the amimo acid residues at position His 32 and Thr 33 of bovine α\|lactalbumin cDNA were substituted with Leu and Glu,respectively.Thus,the catalytic site of lysozyme was obtained in α\|lactalbumin.Furthermore,Tyr 103 was substituted by Ala and the lysozyme substrate binding conformation was formed in α\|lactalbumin as well.The structural as well as functional relationship between α\|lactalbumin and lysozyme indicated that there existed possible evolutionary correlation between the two proteins.展开更多
文摘目的可致肿瘤细胞死亡的人α乳清蛋白(human alpha-lactalbumin made lethal to tumor cells,HAMLET)是一种可导致多种癌细胞死亡的强效选择性肿瘤杀伤蛋白质-脂酸复合物。为了使HAMLET应用于肿瘤的治疗并对其杀伤机制进行探讨,我们需要建立和优化简便、快速、规模化制备与纯化HAMLET的方法。方法通过构建人α乳清蛋白分泌型细胞MCF-7的cDNA文库,PCR扩增出编码人α乳清蛋白成熟肽段的全长序列,然后克隆入pET30a(+)表达载体质粒,并转化BL21(DE3)宿主大肠杆菌。经过IPTG诱导,表达细菌的裂解,蛋白体外复性,Ni-NTA亲和层析柱纯化等步骤,获得了高纯度的重组人α乳清蛋白的C端His标签融合蛋白。纯化蛋白经EDTA脱钙后,与油酸(oleic acid,OA)在加热条件下制备HAMLET复合物。同时,对HAMLET的理化特性和生物学活性进行检测。结果通过与经典方法制备的牛α乳清蛋白和OA复合物(BAMLET)进行比较,发现我们制备的HAMLET在紫外吸收光谱、疏水性质特征及肿瘤杀伤活力方面与BAMLET活性相符,并且可引起HeLa肿瘤细胞的凋亡样程序性死亡。结论本研究自主制备的HAMLET成本经济、方法简便且具有较好的规模化放大前景,为日后临床应用奠定基础。
文摘In order to establish a possible evolutionary correlation between α lactalbumin and lysozyme,site\|directed mutagenesis on α\|lactalbumin cDNA was performed to change α\|lactalbumin into lysozyme.The gene of α\|lactalbumin was cloned into phagemid pSK +vector and the single strand template of which was prepared.Thereafter,the mutagenic oligonucleotide primers were designed and used to synthesize the mutated double strand DNA.By means of this site\|directed mutagenesis,the amimo acid residues at position His 32 and Thr 33 of bovine α\|lactalbumin cDNA were substituted with Leu and Glu,respectively.Thus,the catalytic site of lysozyme was obtained in α\|lactalbumin.Furthermore,Tyr 103 was substituted by Ala and the lysozyme substrate binding conformation was formed in α\|lactalbumin as well.The structural as well as functional relationship between α\|lactalbumin and lysozyme indicated that there existed possible evolutionary correlation between the two proteins.