【摘要】 我们用T₄RNA连接酶,通过两条路线分别将GpUpCpU,CpCpGpG和TpψpCpG三个寡核苷酸片段连接成十二核苷十一磷酸,GpUpCpU³²pCpCpGpG³²pTpψpCpG,即相当于酵母丙氨酸转移核糖核酸分子中顺序46～57的一段序列。我们找到了供体3′-端不带磷或其他保护基时,其自聚或自身环化的产生都不明显的条件,从而使供受体用量比大大降低。在有的情况下,供体量大于受体,也获得了比较满意的连接产率。此外,在我们的实验中,5′端是二个稀有嘧啶碱基T和ψ的供体³²pTpψpCpG与受体CpCpGpG连接的产率不低于由普通碱基供体的连接产率。我们合成的GpUpCpU³²pCpCpGpG³²TpψpCpG已用于酵母丙氨酸转移核糖核酸3′端半分子和全分子的合成中。更多还原

【Abstract】 In this article, the joining of three tetranucleotide fragments, GpUpCpU,Cp Cp Gp G and Tpφp Cp G, to form a dodecanucleotide fragment in the region （46～57） of the 3’-half molecule of yeast alanine tRNA through the catalytic action ofT₄ RNA ligase by two different pathways was investigated. We tried to find theproper conditions under which self-ligation among donor molecules were not obviousin the absence of a protecting group at the 3’-terminus of the donor. The sameconsideration may also be applied to intramolecular oyclization of the same donormolecule （length up to octanucleotide and so on）, for instance, no obvious intramol-ecular cyclization of ³²p Cp Cp Gp G ³²p Tp φp Cp G in our experiment was observed.The molar ratio of acceptor to donor was thus greatly reduced. In some cases,increase of ligation yield may occur when the amount of donor is higher than that ofacceptor. It was also found that T₄RNA ligase catalyzed the joining of a donor ³²pTpφCpG containing two minor bases T and U, at its 5’-terminus with the sameefficiency as other common bases, to accepter Cp Cp Gp G. Gp Up Cp U³² p Cp Cp Gp G³²p Tpφp Cp G has been applied to the synthesis of the 3’-half molecule and wholemole cuk of yeast alanine tRNA.更多还原