RESUMO
Gel-filtered human platelets (GFP) display only a single binding site for [3H]-PGI2: KD = 61nM, 234 fmol/10(8) platelets (1410 sites/platelet). Platelet-rich plasma (PRP) displays the same receptor density but the KD value increases to 123 nM due to protein binding of PGI2 which lowers its effective concentration. The [3H]-PGI2/GFP binding assay has been used to evaluate the molecular basis of aggregation inhibition for prostacyclin analogs and mimics, three PGE type structures, and PGD2. Antiaggregatory IC50s and radioligand binding IC50s correlate for PGE2, E1, and six PGI2 analogs. PGD2, and to a lesser extent 6-oxo-PGE1, display greater antiaggregatory potency than expected based on PGI2-binding site affinity data.
Assuntos
Plaquetas/ultraestrutura , Agregação Plaquetária/efeitos dos fármacos , Receptores de Prostaglandina/fisiologia , Sítios de Ligação , Cromatografia em Gel , Reações Cruzadas , Epoprostenol/metabolismo , Humanos , Receptores de Epoprostenol , TrítioRESUMO
A systematic study of the mass spectral fragmentation of the methyl ester-methyloxime-trimethylsilyl ether derivatives of D and E prostaglandins and selected omega-chain analogs is presented. Fragments from the omega-chain analogs are shifted the appropriate mass when compared with the parent PGD2 or PGE2. NMR data of the methyloxime methyl ester of PGE2 have permitted assignment of the syn and anti isomers (relative to the alpha chain) to the fast and slow eluting gas chromatographic peaks, respectively.
Assuntos
Oximas/análise , Prostaglandinas D/análise , Prostaglandinas E/isolamento & purificação , Silício/análise , Compostos de Trimetilsilil/análise , Fenômenos Químicos , Química , Dinoprostona , Cromatografia Gasosa-Espectrometria de Massas , Espectroscopia de Ressonância Magnética , Prostaglandina D2 , Prostaglandinas E/análise , EstereoisomerismoAssuntos
Prostaglandinas , Tromboxanos , Ácido Araquidônico , Ácidos Araquidônicos/metabolismo , Epoprostenol/metabolismo , Concentração de Íons de Hidrogênio , Conformação Molecular , Oxirredução , Endoperóxidos de Prostaglandina , Prostaglandinas/metabolismo , Análise Espectral , Estereoisomerismo , Terminologia como Assunto , Tromboxanos/metabolismoRESUMO
Prostaglandin H2 displays at 500 MHz a detailed 1H-NMR in which all methylene groups are non-equivalent in C6D6 solution. The spectrum was assigned by analogy to isosteric structures. The dissymmetric perturbation and steric hindrance of the bicyclo [2.2.1] core caused by the side-chains provides a rationale for the selective fragmentations which PGH2 undergoes. Purified PGH2 is considerably more robust than previous literature accounts suggest. The following transformations were monitored by 1H-NMR: 1) O-O bond cleavage by Ph3P , 2) aqueous media fragmentation to PGE2 and PGD2, 3) base catalyzed fragmentation to ketoaldehydes , and 4) thermolysis attempts.
