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Purines, pyrimidines and nucleosides absorption by Li-, Na-, Mg- and Ca-montmorillonite in aqueous solutions over range pH 2-12 by cation exchange
Absorption of nucleosides, purine and pyrimidine derivatives by Co-, Cu- and Ni-montmorillonite taking place by cation exchange process
Pyrimidine and purine bases analysis by time of flight mass spectrometry and paper chromatography
Pyrimidine polyribonucleotides or purine polyribonucleotides binding to lysine- or arginine-rich proteinoids considered for abiogenesis
Free radical formation in irradiated pyrimidines from ESR spectrum analysis of gamma irradiated single crystals of alloxantin, confirming radical stability
Dilute (0.1 M) solutions of HCN condense to oligomers at pH 9.2, and hydrolysis of these oligomers yields 4,5-dihydroxypyrimidine, orotic acid, 5-hydroxyuracil, adenine, 4-aminoimidazole-5-carboxamide, and amino acids. It is suggested that the three main classes of nitrogen-containing biomolecules - purines, pyrimidines, and amino acids may have originated from HCN on the primitive earth. It is also suggested that the presence of orotic acid and 4-aminoimidazole-5-carboxamide might indicate that contemporary biosynthetic pathways for nucleotides evolved from the compounds released on hydrolysis of HCN oligomers.
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Hydrogen bonding of derivatives of guanosine and cytidine soluble in chloroform studied in IR, CONFIRMING geometrical specificity in two-stranded nucleic acids
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Synthetic, structural, and computational approaches were used to solve the puzzle as to how a phenolic nonsteroidal estrogen 1 with only a single H-bond to its receptor was more potent than an isomer 2 which formed an intricate network of H-bonds. Synthesis of a series of substituted phenols revealed that pK a was not a determinant of estrogenic activity. First-principles calculation also failed to explain the difference in activity of 1 and 2. Molecular dynamics revealed that 1 formed a more stable receptor complex compared to 2, which may explain its increased activity despite forming fewer apparent H-bonds with the protein.
Chemically modified antisense oligonucleotides (ASO) currently in pre–clinical and clinical experiments mainly focus on the 2’–position derivatizations to enhance stability and targeting affinity. Considering the possible incompatibility of 2’–modifications with RNase H stimulation and activity, we have hypothesized that the atom specific modifications on nucleobases can retain the complex structure and RNase H activity, while enhancing ASO's binding affinity, specificity, and stability against nucleases. Herein we report a novel strategy to explore our hypothesis by synthesizing the deoxynucleoside phosphoramidite building block with the seleno–modification at 5–position of thymidine, as well as its Se–oligonucleotides. Via X–ray crystal structural study, we found that the Se–modification was located in the major groove of nucleic acid duplex and didn't cause the thermal and structural perturbations. Surprisingly, our nucleobase–modified Se–DNAs were exceptionally resistant to nuclease digestion, while compatible with RNase H activity. In conclusion, this affords a novel avenue for potential anti–sense modification in the form of Se–antisense oligonucleotides (Se–ASO).
Biochemically active Cu(II) and Zn(II) complexes [CuL(ClO{sub 4}){sub 2}(1) and ZnL(ClO{sub 4}){sub 2}(2)] have been synthesized from N,N donor Schiff base ligand L derived from4,6-dichloropyrimdine-5-carboxaldehyde with 4-(2-aminoethyl)morpholine. The L, complexes 1 and 2 have been structurally characterized by elemental analysis, {sup 1}H-NMR, FTIR, MS, UV-Visible and ESR techniques. The results obtained from the spectral studies supports the complexes 1 and 2 are coordinated with L through square planar geometry. DFT calculations results supports, the ligand to metal charge transfer mechanism can occur between L and metal(II) ions. The antimicrobial efficacy results have been recommended that, complexes 1 and 2 are good anti-pathogenic agents than ligand L. The interaction of complexes 1 and 2 with calf thymus (CT) DNA has been studied by electronic absorption, viscometric, fluorometric and cyclic voltammetric measurements. The calculated K{sub b} values for L, complexes 1 and 2 found from absorption titrations was 4.45 × 10{sup 4}, L; 1.92 × 10{sup 5}, 1 and 1.65 × 10{sup 5}, 2. The Ksv values were found to be 3.0 × 10{sup 3}, 3.68 × 10{sup 3}and 3.52 × 10{sup 3} for L, complexes 1 and 2 by using competitive binding with ethidium bromide (EB). These results suggest that, the compounds are interacted with DNA may be electrostatic binding. The molecular docking studies have been carried out to confirm the interaction of compounds with DNA. Consequently, in vitro anticancer activities of L, complexes 1 and 2 against selected cancer (lung cancer A549, liver cancer HepG2 and cervical carcinoma HeLa) and normal (NHDF) cell lines were assessed by MTT assay.
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