In order to prepare pyrimidine nucleoside-peptide conjugate concisely, we developed a one-pot synthetic strategy. Started from uridine, 5-S-acetyl-thiomethyl-2＇,3 ＇-di-O-isopropylidene-uridine （4） was synthesized as the key intermediate in four steps. Under acidic condition, compound 4 was deprotected and reacted with PySS-R （8, 12, 15, Py = 2-pyridyl, R = amino acid or peptide） in one pot to form uridine conjugates （9, 13, 2） with disulfide bond as linker.
Aptamers that interact with various HIV-1 proteins,such as reverse transcriptase,Rev,Tat protein,and nuclear capsule protein,have been prepared through SELEX (systematic evolution of ligands by ex-ponential enrichment) technique. However,there are few reports about the DNA or RNA aptamers that target HIV-1 integrase. In this investigation,we selected alternative RNA aptamers specific for the HIV-1 integrase by using a different binding buffer containing 10 mmol·L-1 MgCl2 and 100 mmol·L-1 KCl. Aptamer IN1,IN2,IN3 had similar and the highest Kd values from 145 to 239 nmol·L-1. Structural studies showed that they formed similar stem-loop structure. Deletion of any stem structure resulted in diminished affinity. In addition,structure probing study with antisense DNA indicated that the stem-loop structure in the random region was critical for integrase binding. Although aptamer IN1 failed to form G-quartet structure,it might directly interact with the DDE motif of integrase,which is the virus DNA-binding site,because G-quadruplex T40214 competitively inhibited the interaction between IN1 and integrase. Together,this study generated a novel RNA aptamer IN1,which could be useful in basic research and anti-HIV drug screening.
LIU YingChunZHANG YanYE GuoZhuYANG ZhenJunZHANG LiangRenZHANG LiHe
To design and synthesize neamine analogues modified at 5 position offing Ⅱ, which could improve the binding affinity of aminoglycosides to 16S RNA. Started from neomycin B, modified neamine analogues were synthesized through organic reactions such as hydrolysis, protection, nucleophilic substitution, deprotection and reduction. The interaction of the target compounds with A-site RNA in E. coli. ribosome （16S RNA） was determined by surface plasmon resonance （SPR）, respectively. Six target compounds were synthesized. Some of them showed antibacterial activities and enhanced affinity to 16S RNA at 10^-3M in vitro. Introduction amino or aliphatic amino group at 5 position offing Ⅱ in neamine would maintained antibacterial activities as well as increase binding affinity to 16S RNA. Furthermore, there is almost no influence on the stability of drug/16S RNA complex by inverting the configuration of 5-hydroxyl group at ring Ⅱ.
