生长激素释放因子(GRF)的基因改造及化学合成

Chemical Synthesis and Cloning of Modified GRF Gene

为了提高生长激素释放因子（ＧＲＦ）的体内活性，根据猪ＧＲＦ的天然序列，设计了改造后ＧＲＦ（１～３２）的基因序列（含信号肽），两端加设ＥｃｏＲＩ、ＨｉｎｄⅢ的粘性末端，分４段由ＤＮＡ合成仪合成，每段长度分别为９５、９７、８６、１０６ＮＴ，２条链间有１５个碱基的粘端。用尿素变性ＰＡＧＥ纯化合成片段，用Ｔ４多核苷酸激酶对合成ＤＮＡ磷酸化，混合４个片段复性，然后用Ｔ４连接酶连接。提取ｐＢｌｕｓｃｒｉｐｔ质粒，用ＥｃｏＲＩ和ＨｉｎｄⅢ在Ｍｕｌｔｉｃｏｒｅｂｕｆｅｒ中酶切完全后，琼脂糖电泳，由ＧｅｎｅＥｌｕｔｅＡｇｒｏｓｅＳｐｉｎＣｏｌｕｍｓ回收酶切大片段。将该酶切片段与上述合成的ＧＲＦ基因由Ｔ４连接酶连接，并转化至氯化钙致敏的ＤＨ５α。选取重组菌落，提取质粒，用ＰＣＲ及双酶切鉴定阳性克隆。用Ｍｉｎｉｐｒｅｐ提取重组质粒，ＡＢＩ３７３自动测序仪测序。测序结果表明已克隆到合成的ＧＲＦ基因。

Growth hormone releasing factor(GRF) has potential availability in animal husbandry.We synthesized a modified GRF gene which is more powerful and stable in animal body,186 NT in length including signal peptide sequence.Four fregments(106 NT,86 NT,97 NT and 95 NT) were designed,including cohensive end of Eco RI and HindⅢ.The synthesied fregments were purified by PAGE,then phosphoralated by T 4 polynucleiotide kinase.Mixture of those fregments was ligated with prepared pBluscript Eco RI HindⅢ fregment through T 4 DNA ligase.After being transformed to competent DH5α cells,we selected and identified the negative clones by PCR and cutting with Eco RI and HindⅢ.Sequencing result with M13 showed that we have got a modified GRF gene.