三磷酸胞苷在Duolite A-30树脂上的交换过程研究

根据CTP在离子交换树脂上的吸附容量和分离因数的大小,确定Duolite A-30树脂适合CTP与CDP,CMP之间的分离.对CTP在Duolite A-30树脂上的吸附动力学和热力学研究表明,在283.15K~303.15K之间,CTP的质量浓度在7.5g/L以上时,Duolite A-30树脂对CTP的吸附主要受颗粒扩散的控制,其有效扩散系数为D=3.47×10-7cm2/s,溶液的质量浓度≤1.0g/L时,CTP与Duolite A-30树脂之间的交换速率主要受液膜控制,其液膜扩散系数为Kf =4.112×10-4/s.同时测定了不同条件下三磷酸胞苷溶液在Duolite A-30树脂固定床离子交换柱中的穿透曲线,研究了进口浓度、进口流速、原料液温度、原料液的pH值及柱高对穿透曲线的影响.用二阶动力学推动力模型描述固定床动态过程,考察了轴向返混对穿透曲线的影响,并从穿透曲线回归得到总传质系数,模型计算值与实验数据符合良好.     

Synthesis of 3′-fluoro-4′-amino-hexitol nucleosides with a pyrimidine nucleobase as building blocks for oligonucleotides

The synthesis of 3′-fluoro-4′-amino-hexitol nucleosides with a uracil and cytosine nucleobase was performed. The synthesis started from 1,5:2,3-dianhydro-4,6-benzylidene-allitol and afforded the target compounds in 15 steps. These protected hexitol nucleosides are valuable building blocks for the preparation of a new class of oligonucleotides.     

胞嘧啶核苷在纳米银膜上的NIR-SERS光谱检测

采用一种高活性的纳米银膜作为表面增强拉曼散射(SERS)基底,以近红外激光(785 nm)作为激发光源,对胞嘧啶核苷(胞苷)水溶液(10-2～10-8 mol·L-1)进行了近红外表面增强拉曼散射(NIR-SERS)光谱检测。实验结果表明,当胞苷水溶液浓度等于或低于10-7 mol · L-1时,可在300～2 000 cm-1范围内获得信噪比较好的NIR-SERS光谱。将胞苷水溶液(10-2～10-5 mol · L-1)分别滴在10片不同的纳米银薄膜上进行检测,结果表明该纳米银膜体现出了较好的光谱重现性。通过对纳米银膜表面形貌进行表征发现聚乙烯醇(PVA)包覆的纳米银颗粒在铝片表面形成“草状”结构。并通过对吸附了胞苷分子的纳米银膜进行紫外-可见光反射光谱检测,发现在800 nm处出现等离子共振峰。因此采用785 nm的近红外激光作为激发光时,该体系能够体现出强烈的表面等离子共振(surface plasmon resonance, SPR)特性。同时采用DFT-B3LYP/6-311G对胞苷分子进行了拉曼光谱计算,计算所采用入射光波长为785 nm,通过计算结果与实验测得的胞苷固体的拉曼光谱对比发现在300～2 000 cm-1范围内两者匹配得较好,进而对其振动进行了归属。最后通过比较胞苷的拉曼光谱和NIR-SERS光谱对胞苷分子在纳米银膜上的可能吸附方式进行了分析。分析结果表明胞苷分子主要为其核糖部分吸附纳米银颗粒上,同时该分子的17NH₂基团可能靠近局域电磁场增强区域。     

Equilibrium and spectroscopic studies of ternary cadmium(II) and mercury(II) complexes with CMP and triamines

Formation of ternary Cd(II) and Hg(II) complexes with cytidine 5′-monophosphate (CMP) and triamines has been studied. Complexes M(CMP)(H _x PA) and M(CMP)(PA) (M?=?Cd, Hg; PA?=?polyamine) were detected and overall stability constants and equilibrium constants for their formation determined. The mode of coordination in the complexes has been proposed on the basis of the equilibrium and ¹³C, ³¹P NMR and IR studies. In the Hg(II) systems, metalation involves the donor endocyclic N(3) atom, the CMP phosphate group and nitrogen donor atoms of PA. Relative to the Hg/CMP binary systems, the presence of a polyamine in ternary systems does not change the metal–nucleotide mode of coordination. In ternary systems including Hg(II) ions, the occurrence of noncovalent interactions has not been detected. Cd(II) ions form molecular complexes as well as protonated species. Introduction of a polyamine to the Cd/CMP system changes the coordination mode of the nucleotide. The phosphate group of CMP is inactive in binary complexes (metalation by the N(3) atom) but is involved in coordination in heteroligand species. In contrast to other polyamines studied, in the system including 1,7-diamino-4-azaheptane (3,3-tri), the phosphate group of CMP in Cd(CMP)(H3,3-tri) does not participate in metalation but is engaged in intramolecular noncovalent interactions that stabilize the complex.     

Electrodeposited sol-gel-imprinted sensing film for cytidine recognition on Au-electrode surface

A novel thin molecularly imprinted sol-gel film with specific recognition for cytidine was electrodeposited on the surface of piezoelectric quartz crystal (PQC) Au-electrode. In this method, a sufficiently negative potential was applied to the electrode surface to generate hydroxyl ions, which play the role of the catalyst for the hydrolysis and condensation of 3-(aminopropyl)trimethoxysilane (APTMS). The process of the preparation of the imprinted sol-gel film was investigated in detail by using the piezoelectric quartz crystal impedance (PQCI) technique and cyclic voltammetry. The thickness of the imprinted film was controlled easily by adjusting the applied potential and the deposited time. The binding capacity and the selectivity of the electrodeposited imprinted sol-gel film were also studied in detail by using PQCI, electrochemically impedance technique and capacitance technique. The electrodeposited imprinted sol-gel film exhibited high selectivity toward cytidine in comparison to interfering substances. The dissociation constant (K_d) in the nanomolar range indicated a strong imprinted interaction existing between the electrodeposited sol-gel-imprinted film and the template cytidine.     

Nucleosides XIII. Facile Synthesis of 4‐Amino‐1‐(2‐deoxy‐β‐D‐ribofuranosyl)quinazolin‐2‐one as a 2′‐Deoxycytidine Analog for Oligonucleotide Synthesis

4‐Amino‐1‐(2‐deoxy‐β‐D‐ribofuranosyl)quinazolin‐2‐one (4) was prepared by Barton deoxygenation from 4‐amino‐1‐(β‐D‐ribofuranosyl)quinazolin‐2‐one (3) as a 2′‐deoxycytidine analog.     

Separation of Cytidine 5′-triphosphate Biosynthesized from Cytidine 5′-monophosphate on Ion-exchange Resin and HPLC Analysis of Cytidine Compounds

Conditions were studied in the biosynthesis of cytidine 5′-triphosphate (CTP) from cytidine 5′-monophosphate (CMP). A 201 × 7 anion ion-exchange resin was applied for the separation of CTP from CMP. Adsorption isotherm and elution conditions (eluant, eluant concentration, flow rate, sample volume loaded) were investigated. At the same time, a new high-performance liquid chromatography on an anion ion-exchange column WAX-1 with UV detector at 260 nm was developed to measure CMP, cytidine 5′-diphosphate (CDP), and CTP. The retention time for CMP, CDP, and CTP are 0.723, 1.448, and 4.432 min, respectively. This new rapid high-performance liquid chromatography (HPLC) method for the analysis of cytidine compounds in biological sample has a wide linear range with high precision and repeatability.     

INVESTIGATION OF THE SOLUTION STRUCTURE OF Cu(II) MIXED-LIGAND COMPLEXES OF ADENOSINE 5′-MONOPHOSPHATE AND CYTIDINE 5′-MONOPHOSPHATE AND POLYAMINES

Abstract

The coordination mode of complexes formed in the systems Cu(II)/NMP/PA; (NMP =adenosine 5′-monophosphate, cytidine 5′-monophosphate; PA = 1,4-diaminopropane (putrescine, Put), 1,7-diamino-4-azaheptane (3,3-tri) and 1,11-diamino-4,8-diazaundekane (3,3,3-tet)) was determined on the basis of the equilibrium and spectroscopic studies. The presence of the following mixed complexes was established: Cu(CMP)H(Put), Cu(AMP)H₂(3,3-tri) and Cu(CMP)H₂(3,3-tri), Cu(CMP)H₄(3,3-tri) and coordination compounds of MLL′ type-Cu(CMP)(3,3,3-tet), Cu(AMP)(3,3,3-tet). A significant influence of the polyamine length on the solution structure of the complexes was observed. In mixed-ligand complexes Cu(NMP)(3,3,3-tet) a {N4, O} chromophore is formed, and metallation involves all nitrogen atoms from 3,3,3-tet. In the analogous system with 3,3-tri, protonated complexes occur. Non-covalent intramolecular interaction between the protonated amine groups and donor atoms from the purine ring from the nucleotide results in an increase of complex stability.     

Synthesis of 1,2‐Disubstituted Carbocyclic Nucleoside Analogues of Cytidine

The synthesis of new 1,2‐disubstituted, five‐ or six‐ring‐carbocyclic nucleoside analogues of cytidine, compounds 1 and 2a – d , are described. These compounds were obtained by aminolysis, starting from the corresponding uracil derivative, via nucleophilic displacement of a triazolyl (Scheme 1) or a (2,4,6‐triisopropylphenyl)sulfonyl (TPS) group (Scheme 2) at 4‐position of the pyrimidine ring.