Magnesium ion catalyzed phosphorus-nitrogen bond hydrolysis in imidazolide-activated nucleotides. Relevance to template-directed synthesis of polynucleotides
作者:Anastassia Kanavarioti、Claude F. Bernasconi、Donald L. Doodokyan、Diann J. Alberas
DOI:10.1021/ja00200a053
日期:1989.8
conclusion is based on a study of the N-methylated substrates N-MeImpG and 1,2-diMeImpg, respectively, which were generated in situ by the equilibrium reaction of ImpG with N-methylimidazole and 2-MeImpG with 1,2-dimethylimidazole, respectively. In contrast, the absence of Mg2+ the reaction of S- with water competes with the reaction of SH+/- with OH-. The present study bears on the mechanism of the Mg2(+)-catalyzed
Catalysis of hydrolysis and nucleophilic substitution at the phosphorus-nitrogen bond of phosphoimidazolide-activated nucleotides in phosphate buffers
作者:Anastassia Kanavarioti、Morgan T. Rosenbach
DOI:10.1021/jo00004a032
日期:1991.2
exhibit enhanced rates of degradation in the presence of aqueous inorganic phosphate in the range 4.0 < or = pH < or = 8.6. This degradation is been attributed to (i) nucleophilic substitution of the imidazolide and (ii) catalysis of the P-N bond hydrolysis by phosphate. The first reaction results in the formation of nucleoside 5'-diphosphate and the second in nucleoside 5'-monophosphate. Analysis of the
ro-2-methyl imidazolides on standard oligonucleotide templates has been studied extensively. Here, we describe experiments with templates in which inosinicacid (I) is substituted for guanylicacid, or 2,6-diaminopurine nucleotide (D) for adenylicacid. We find that the substitution of I for G in a template is strongly inhibitory and prevents any incorporation of C into internal positions in the oligomeric
Effects of Monomer and Template Concentration on the Kinetics of Nonenzymatic Template-Directed Oligoguanylate Synthesis
作者:Anastassia Kanavarioti、Claude F. Bernasconi、Eldon E. Baird
DOI:10.1021/ja9807237
日期:1998.9.1
< k2 < ki. This is the first reported study that includes rate determinations of ki as a function of the concentration of both poly(C) template and the activated monomer, guanosine5‘-monophosphate-2-methylimidazolide (2-MeImpG), in the range 2 mM ≤ [poly(C)] ≤ 50 mM and 5 mM ≤ [2-MeImpG] ≤ 50 mM. ki values determined under conditions where the template is fully saturated with monomer are practically
为了确定影响非酶促模板导向寡核苷酸反应效率的关键参数,对多胞苷酸 (poly(C)) 模板上的寡鸟苷酸合成进行了动力学研究。这种低聚反应通过三个动力学过程得到令人满意的描述:(i)二聚化形成第一个引物(k2),(ii)预制引物的延伸(ki,i≥3),以及(iii)单体水解形成失活材料 (kh),kh < k2 < ki。这是第一个报道的研究,其中包括测定 ki 作为聚 (C) 模板和活化单体鸟苷 5'-单磷酸-2-甲基咪唑化物 (2-MeImpG) 浓度的函数,范围为 2 mM ≤ [poly(C)] ≤ 50 mM 和 5 mM ≤ [2-MeImpG] ≤ 50 mM。在模板完全被单体饱和的条件下确定的 ki 值实际上与单体和聚合物浓度无关,因此强烈支持模板导向的伸长模型。ki的值决定...
Use of Phosphoimidazolide-Activated Guanosine to Investigate the Nucleophilicity of Spermine and Spermidine
作者:Anastassia Kanavarioti、Eldon E. Baird、Pearish J. Smith
DOI:10.1021/jo00120a035
日期:1995.7
Guanosine 5'-phosphate 2-methylimidazolide (2-MeImpG), a labile phosphoimidazolide analog of guanosine triphosphate, was used to test the reactivity of the natural polyamines (PAs), spermine (spm) and spermidine(spd); The products are the guanosine 5'-phosphate-polyamine derivatives (PA-pG: spd-pG and spm-pG) which are quite stable in the range 4 < pH < 11. Our study is the first of which we are aware that reports on the nucleophilicity of these amines. The main findings are as follows. (i) HPLC analysis of the products indicates the formation of only two of the three possible spd products and only one of the two possible spm products. These results can be explained if only the primary amino groups of the two polyamines are reactive, while the secondary amino groups are rendered unreactive by a steric effect. The reactions of 2-MeImpG and other phosphoimidazolide derivatives of nucleosides (ImpNs) with primary and secondary monoamines support this interpretation (Kanavarioti et al. J. Org. Chem. 1995, 60, 632). (ii) The product ratio of the two spd-pG adducts derived from the primary amino groups varies between 2.40, and 0.71 in the range 6.1 less than or equal to pH less than or equal to 11.9. Such small variation in the product ratio can only be rationalized by the similar, but not identical, basicity of the two primary amino groups and provides strong support for a previously reported model for polyamine ionization (Onasch et. al. Biophys. Chem. 1984, 19, 245). (iii) On the basis of our kinetic determinations conditions at which the nucleophilicity of these amines is at a minimum and at which other interactions with ImpNs could be tested can be chosen.