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1.
K. I. Mikhailopulo T. S. Serchenya E. P. Kiseleva Yu. G. Chernov T. M. Tsvetkova N. V. Kovganko O. V. Sviridov 《Journal of Applied Spectroscopy》2008,75(6):857-863
We have used fluorescence spectroscopy methods to show that imidacloprid and its structural analogs form complexes with human
serum albumin (HSA). The nature of the spectral changes in the ligand×protein systems and the calculated complexation parameters
suggest that these low molecular weight compounds mainly bind to a specific section of the protein molecule, near the tryptophan
residue in the 214 position of the polypeptide chain. We have found that the association constants are on the order of 104 M−1, and the affinity of the ligands for HSA varies in the series 6-chloronicotinic acid > 6-methoxynicotinic acid = imidacloprid
> the keto analog of imidacloprid. The major contribution to the complexation energy probably comes from hydrophobic interaction
forces with participation of the aromatic pyridine ring of the ligands, while additional enhancement of ligand-protein affinity
can be provided by the nitroimine group of imidacloprid.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 859–866, November–December, 2008. 相似文献
2.
Mikhailopulo IA Pricota TI Sivets GG Altona C 《The Journal of organic chemistry》2003,68(15):5897-5908
The synthesis of methyl 5-O-benzoyl-2-chloro-2,3-dideoxy-3-fluoro-beta-d-ribofuranoside (5) and its use as a glycosylating agent for persilylated thymine, N(6)-benzoyladenine, and N(4)-benzoylcytosine are described (Scheme 1). The 2'-chloro-2',3'-dideoxy-3'-fluoro-d-ribonucleosides 10-12 synthesized were transformed to 2',3'-dideoxy-3'-fluoro-alpha- and -beta-d-erythro-pentofuranoside nucleosides of thymine (13a,b), adenine (14a,b), and cytidine (15a,b) by treatment with tributyltin hydride in the presence of alpha,alpha'-azobisisobutyronitrile (Scheme 2). Treatment of 2'-chloro-2',3'-dideoxy-3'-fluoro-d-ribonucleosides with 1 M MeONa/MeOH under reflux for 1-5 h afforded 2',3'-didehydro-2',3'-dideoxy-2'-chloro-d-pentofuranosyl nucleosides as the principal products (47-81%) of the reaction, along with recovered starting nucleoside (11-33%) (Scheme 3). Easy HF elimination was also observed in the case of the 2'-azido-2',3'-dideoxy-3'-fluoro-beta-d-ribofuranosides of thymine (17) and adenine (20) (Scheme 3). The role of conformational peculiarities of 2'-chloro-2',3'-dideoxy-3'-fluoro-d-ribonucleosides as well as of 17 and 20 in the observed exclusive elimination of HF is discussed. The conformational analysis of a rather broad palette of 2,3-dideoxy-3-fluoro-2-(X-substituted)-d-ribofuranosides was performed with the aid of the PSEUROT (version 6.3) program, using (i) the recently reparametrized Karplus-type relation (Chattopadhyaya and co-workers. J. Org. Chem. 1998, 63, 4967) and (ii) empirical bond angle correction terms suggested by us. The predictive power of the Brunck and Weinhold model (J. Am. Chem. Soc. 1979, 101, 1700) of the gauche effect between atoms and groups as a conformational driving force acting upon the pentofuranose ring is explored. Their model invokes maximum antiperiplanar sigma <--> sigma stabilization when the donating bond is the least polar one and the acceptor orbital is at the most polarized bond and is found at least as satisfactory, and in various specific cases more so than, as rationalizations on the basis of the preference of the gauche vs the trans conformation of two vicinal electronegative substituents (Wolfe. Acc. Chem. Res. 1972, 5, 102). 相似文献
3.
Grigorii G. Sivets Elena N. Kalinichenko Igor A. Mikhailopulo 《Helvetica chimica acta》2007,90(9):1818-1836
Convergent syntheses of the 9‐(3‐X‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranosyl)adenines 5 (X=N3) and 7 (X=NH2), as well as of their respective α‐anomers 6 and 8 , are described, using methyl 2‐azido‐5‐O‐benzoyl‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranoside ( 4 ) as glycosylating agent. Methyl 5‐O‐benzoyl‐2,3‐dideoxy‐2,3‐difluoro‐β‐D ‐ribofuranoside ( 12 ) was prepared starting from two precursors, and coupled with silylated N6‐benzoyladenine to afford, after deprotection, 2′,3′‐dideoxy‐2′,3′‐difluoroadenosine ( 13 ). Condensation of 1‐O‐acetyl‐3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐β‐D ‐ribofuranose ( 14 ) with silylated N2‐palmitoylguanine gave, after chromatographic separation and deacylation, the N7‐β‐anomer 17 as the main product, along with 2′‐deoxy‐2′‐fluoroguanosine ( 15 ) and its N9‐α‐anomer 16 in a ratio of ca. 42 : 24 : 10. An in‐depth conformational analysis of a number of 2,3‐dideoxy‐2‐fluoro‐3‐X‐D ‐ribofuranosides (X=F, N3, NH2, H) as well as of purine and pyrimidine 2‐deoxy‐2‐fluoro‐D ‐ribofuranosyl nucleosides was performed using the PSEUROT (version 6.3) software in combination with NMR studies. 相似文献
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5.
V. I. Gunar L. F. Ovechkina I. A. Mikhailopulo S. I. Zav'yalov 《Russian Chemical Bulletin》1968,17(4):883-885
Conclusions The reaction of urea with-alkyl--formylcarboxylate esters and oxalacetic ester in oleum gives 5-alkyluracils and orotic acid, respectively.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 918–920, April, 1968. 相似文献
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8.
A. A. Akhrem I. A. Mikhailopulo A. F. Abramov 《Magnetic resonance in chemistry : MRC》1979,12(4):247-253
Structural correlations have been carried out from 13C chemical shifts (δ) and by analysis of 1J(CH) coupling constants, and the conformation about the glycosidic bond has been studied by means of the 3J(CH) vicinal coupling constants between C-8 and H-1′ of some adenine nucleosides such as adenosine (Ado), N(7)-β-D-ribofuranosyladenine (N(7)-Ado), N(9)- and N(7)-β-D-xylofuranosyladenine (N(9)-xylAde and N(7)-xylAde), N(9)-(3-chloro-3-deoxy-β-D-xylofuranosyl)adenine (3′-Cl-xylAde) and N(9)-(2-chloro-2-deoxy-β-D-arabinofuranosyl)adenine (2′-Cl-araAde). The analysis of the influence on δ13C of the nature and configuration of the substituent in the carbohydrate fragment of the molecule has revealed two types of effects, namely, 1,2-cis and 1,2-trans. This approach, as well as the 3J(CH) values and the analysis of the C-3′-endo?C-2′-endo equilibrium of the carbohydrate fragment of nucleosides, and circular dichroism (CD) data, provides important information on the conformation about the glycosidic bond. The magnitudes of 3J(C-4, H) are indicative of the position of attachment of the carbohydrate fragment to the heterocyclic base. 相似文献
9.
Barchi JJ Karki RG Nicklaus MC Siddiqui MA George C Mikhailopulo IA Marquez VE 《Journal of the American Chemical Society》2008,130(28):9048-9057
The conformations of three 2',3'-difluoro uridine nucleosides were studied by X-ray crystallography, NMR spectroscopy, and ab initio calculations in an attempt to define the roles that the two vicinal fluorine atoms play in the puckering preferences of the furanose ring. Two of the compounds examined contained fluorine atoms in either the arabino or xylo dispositions at C2' and C3' of a 2',3'-dideoxyuridine system. The third compound also incorporated fluorine atoms in the xylo configuration on the furanose ring but was substituted with a 6-azauracil base in place of uracil. A battery of NMR experiments in D 2O solution was used to identify conformational preferences primarily from coupling constant and NOE data. Both (1)H and (19)F NMR data were used to ascertain the preferred sugar pucker of the furanose ring through the use of the program PSEUROT. Compound-dependent parameters used in the PSEUROT calculations were newly derived from complete sets of conformations calculated from high-level ab initio methods. The solution and theoretical data were compared to the conformations of each molecule in the solid state. It was shown that both gauche and antiperiplanar effects may be operative to maintain a pseudodiaxial arrangement of the C2' and C3' vicinal fluorine atoms. These data, along with previously reported data by us and others concerning monofluorinated nucleoside conformations, were used to propose a model of how fluorine influences different aspects of nucleoside conformations. 相似文献
10.
VladimirN. Barai AnatoliI. Zinchenko LudmillaA. Eroshevskaya ElenaV. Zhernosek Erik DeClercq IgorA. Mikhailopulo 《Helvetica chimica acta》2002,85(7):1893-1900
9‐(3‐Deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2,6‐diaminopurine ( 6 ) was synthesized by an enzymatic transglycosylation of 2,6‐diaminopurine ( 2 ) with 3′‐deoxycytidine ( 1 ) as a donor of 3‐deoxy‐D ‐erythro‐pentofuranose moiety. This transformation comprises i) deamination of 1 to 3′‐deoxyuridine ( 3 ) under the action of whole cell (E. coli BM‐11) cytidine deaminase (CDase), ii) the phosphorolytic cleavage of 3 by uridine phosphorylase (UPase) giving rise to the formation of uracil ( 4 ) and 3‐deoxy‐α‐D ‐erythro‐pentofuranose‐1‐O‐phosphate ( 5 ), and iii) coupling of the latter with 2 catalyzed by whole cell (E. coli BMT‐4D/1A) purine nucleoside phosphorylase (PNPase). Deamination of 6 by adenosine deaminase (ADase) gave 3′‐deoxyguanosine ( 7 ). Treatment of 6 with NaNO2 afforded 9‐(3‐deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2‐amino‐6‐oxopurine (3′‐deoxyisoguanosine; 8 ). Schiemann reaction of 6 (HF/HBF4+NaNO2) gave 9‐(3‐deoxy‐β‐D ‐erythro‐pentofuranosyl)‐2‐fluoroadenine ( 9 ). 相似文献