作业帮IPTG加入E. Coli.之后,在beta半乳糖苷酶表达活性之前出现延迟,说明了什么
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IPTG加入E. Coli.之后,在beta半乳糖苷酶表达活性之前出现延迟,说明了什么
Synthesis of beta-galactosidase has been induced in glycerol-grown E.Coli cells by addition of IPTG.
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Was there a delay after addition of IPTG before the beta-galactosidase activity began to rise? If so ,what might that present?
Synthesis of beta-galactosidase has been induced in glycerol-grown E.Coli cells by addition of IPTG.
.
Was there a delay after addition of IPTG before the beta-galactosidase activity began to rise? If so ,what might that present?
－半乳糖苷酶的活性在含有乳糖操纵子的E.Coli内一直有的,处于低水平渗漏表达状态,加入IPTG以后,阻遏蛋白失活,操纵子中的b-半乳糖苷酶开始被诱导表达,此时随着表达的进行,酶在细胞内的浓度迅速上升,活性大大提高,基本上没有延迟.在原核诱导表达系统中,使用IPTG不需要经过半乳糖苷酶催化就具有结合能力（乳糖需要经过该酶催化才能产生有活性的分子）所以半乳糖苷酶除了作为报告基因基本上没什么用处.如果是乳糖诱导,该酶的活性上升就比较慢了,因为渗漏表达的半乳糖苷酶量很少,要催化足够产生诱导作用的半乳糖需要较长的一段时间.