RESUMEN
The synthesis of three heparin analogues (i.e. compounds VI-VIII) having perphosphorylated thrombin binding domains (TBDs) is reported. These compounds were tested in vitro for their antithrombin III (ATIII)-mediated anti-Xa and antithrombin activities. Conjugates VI and VIII show a remarkable increase in antithrombin activity compared to the structurally related conjugates with persulfated TBDs (i.e. compounds IV and V), whereas compound VII displays a diminished activity.
Asunto(s)
Antitrombinas/síntesis química , Heparina/análogos & derivados , Trombina/metabolismo , Antitrombinas/química , Antitrombinas/metabolismo , Sitios de Unión , Conformación de Carbohidratos , Secuencia de Carbohidratos , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Datos de Secuencia Molecular , FosforilaciónRESUMEN
The syntheses of several heparin-like glycoconjugates (i.e., 16a-f) containing identical AT III binding domains (ABD) and spacers but different thrombin binding domains (TBDs) are described. Biological activities of conjugates 16a-f indicate that the thrombin inhibitory activity is mainly determined by the charge density of the TBD moiety.
Asunto(s)
Glicoconjugados/síntesis química , Glicoconjugados/farmacología , Heparina/análogos & derivados , Heparina/farmacología , Oligosacáridos/síntesis química , Trombina/metabolismo , Angiotensina III/metabolismo , Sitios de Unión , Conformación de Carbohidratos , Secuencia de Carbohidratos , Dermatán Sulfato/química , Diseño de Fármacos , Glicoconjugados/química , Modelos Moleculares , Datos de Secuencia Molecular , Oligosacáridos/química , Oligosacáridos/farmacología , Relación Estructura-ActividadRESUMEN
The in vitro antithrombotic activity of synthetic glycoconjugates I and II, comprising a flexible polyethylene glycol type and a rigid polyglucose type spacer, respectively, are compared to heparin.
Asunto(s)
Anticoagulantes/farmacología , Glicoconjugados/farmacología , Heparina/análogos & derivados , Heparina/farmacología , Polietilenglicoles/farmacología , Trombina/antagonistas & inhibidores , Anticoagulantes/síntesis química , Anticoagulantes/química , Conformación de Carbohidratos , Secuencia de Carbohidratos , Inhibidores del Factor Xa , Glicoconjugados/síntesis química , Glicoconjugados/química , Heparina/síntesis química , Heparina/química , Humanos , Datos de Secuencia Molecular , Factor Plaquetario 4/antagonistas & inhibidores , Polietilenglicoles/síntesis química , Polietilenglicoles/química , Relación Estructura-ActividadRESUMEN
Electrostatic interactions appear to be important in the conformation and dynamics of DNA four-way junctions. Particularly, the Coulomb repulsion between two approaching phosphate groups at the site of strand exchange is commonly supposed to have a negative influence on the thermodynamic stability of the fully stacked conformation. We synthesized a unimolecular DNA four-way junction containing an uncharged methylene-acetal linkage, -O3'-CH2-O5'-, instead of a regular phosphodiester linkage, -O3'-PO2-O5'-, between two specific residues at the branch-point to examine the effect of charge removal. Complete sequential 1H-NMR assignments of the non-exchangeable base protons and H1'/H2'/H2" sugar protons were obtained with the aid of NOESY and TOCSY experiments. On the basis of the NMR data it is concluded that the stacking arrangement at the branch-point of the modified oligonucleotide is similar to that of the previously studied parent four-way junction. Surprisingly, this is not the stacking arrangement in which the close phosphate-phosphate contact at the site of strand exchange would be absent. Some implications of this novel information regarding the role of the phosphate-phosphate repulsion in four-way junctions are discussed.
Asunto(s)
ADN/química , Conformación de Ácido Nucleico , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Oligonucleótidos/química , Isótopos de Fósforo , Protones , TritioRESUMEN
The naturally occurring DNA-nucleopeptide H-Asp-Ser[5'-pAAAGTAAGCC-3']-Glu-OH was prepared via a solid-phase phosphite triester approach using N-2-(tert-butyldiphenylsilyloxymethyl)benzoyl protected nucleosides. The oligonucleotide was linked via the extremely base-labile oxalyl ester anchor to the solid support.
Asunto(s)
Bacteriófagos/química , ADN Viral/síntesis química , Nucleoproteínas/síntesis química , Fragmentos de Péptidos/síntesis química , Proteínas Virales/síntesis química , Secuencia de Aminoácidos , Bacillus subtilis/química , Bacillus subtilis/genética , Bacteriófagos/genética , Secuencia de Bases , Datos de Secuencia MolecularRESUMEN
The naturally occurring RNA-nucleopeptide H-Ala-Tyr[5'-pUUAAAAC-3']-NH2 is prepared via a solid-phase phosphite triester approach using N-SiOMB/O-TBDMS-protected nucleosides. Preliminary 1H-NMR studies show that the peptidyl unit has a remarkable effect on the conformational behaviour of the RNA moiety in the nucleopeptide.
Asunto(s)
Oligorribonucleótidos/química , Fragmentos de Péptidos/síntesis química , Poliovirus/química , ARN Viral/química , Ribonucleoproteínas/síntesis química , Proteínas Virales/síntesis química , Espectroscopía de Resonancia Magnética , Conformación de Ácido Nucleico , Nucleoproteínas/química , Fragmentos de Péptidos/química , Ribonucleoproteínas/química , Proteínas Virales/químicaRESUMEN
The preparation of the nucleopeptide H-Phe-Tyr-(pATAT)-NH2 could be realized via a solid phase phosphitetriester approach and by using the protected protecting group 2-(tert-butyldiphenylsilyoxymethyl)-benzoyl for the masking of the N6-amino function of deoxyadenosine. The latter protecting group can be removed under mild conditions with fluoride ion.
Asunto(s)
Bacteriófago phi X 174 , Nucleoproteínas/síntesis química , Oligopéptidos/síntesis química , Bacteriófago phi X 174/análisis , CromatografíaRESUMEN
Use of the protecting groups di-n-butylaminomethylene,2-nitrophenylsulfenyl and the ester of 2-(hydroxymethyl)-9,10-anthraquinone, enabled us for the first time to prepare nucleopeptide fragments containing 2'-deoxyguanosine and a free carboxylic acid group.