抗肿瘤细胞多药抗性基因MDR1和MRP1双靶位自剪切核酶的合成及其在体外活性研究

多药耐药基因MDR1和 (或 )MRP1过度表达是引起肿瘤细胞对化疗药物产生多重耐药性的重要原因 .在以往研究抗MDR1基因的核酶 (196MDR1 Rz)的基础上 ,合成了针对MRP1基因 2 10和 730编码子的核酶 (2 10MRP1 Rz ,730MRP1 Rz) ,同时利用RNA二级结构分析程序mfold 3 0设计合成了一种双靶位自剪切核酶体系 (Coat) .将 196MDR1 Rz和 2 10MRP1 Rz基因同时载入到该体系中 ,建立了抗MDR1 MRP1双靶位核酶 .在无细胞体系中对上述核酶进行的生物活性实验表明 ,2 10MRP1 Rz与 730MRP1 Rz相比能够更有效地切割底物 ;载入Coat的抗MDR1和MRP1核酶均能得以有效释放 ,同时切割各自的靶RNA序列 ,切割效率与单靶位核酶一致 ;串联核酶的先后顺序不影响切割活性     

Catechol as a nucleophilic catalyst of peptide bond formation.

The aminolysis of a mildly activated aminoacid ester, benzyloxycarbonyl-L-phenylalanine cyanomethyl ester, by glycine esters in the presence of catechol has been studied as a model of catalysis by RNA cis-vicinal-diol systems in protein biosynthesis. Catechol accelerated the aminolysis, especially in the presence of bases, probably by nucleophilic catalysis.     

The RNA dreamtime

Modern cells present no signs of a putative prebiotic RNA world. However, RNA coding is not a sine qua non for the accumulation of catalytic polypeptides. Thus, cellular proteins spontaneously fold into active structures that are resistant to proteolysis. The law of mass action suggests that binding domains are stabilized by specific interactions with their substrates. Random polypeptide synthesis in a prebiotic world has the potential to initially produce only a very small fraction of polypeptides that can fold spontaneously into catalytic domains. However, that fraction can be enriched by proteolytic activities that destroy the unfolded polypeptides and regenerate amino acids that can be recycled into polypeptides. In this open system scenario the stable domains that accumulate and the chemical environment in which they are accumulated are linked through self coding of polypeptide structure. Such open polypeptide systems may have been the precursors to the cellular ribonucleoprotein (RNP) world that evolved subsequently.