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1.
The surface interaction of C-phycocyanin with lipids was studied using the monolayer technique. The surface activity of the protein was found to be higher at the lipid-water interface than at the nitrogen-water interface, particularly at high surface pressures of the lipid monolayer. The maximum initial surface pressures beyond which phycocyanin could not penetrate the dipalmitoylphosphatidylcholine and monogalactosyldiglycerol monolayers were 27 and 30 mN m-1, respectively. Below these values the protein demonstrated preferential interaction with the monogalactosyldiglycerol monolayer. The surface properties of the unfolded protein at pH 2.5 at the lipid-water interface were compared with those of the protein at pH 7.0. Higher affinity of the three-dimensional structure of the protein to lipid monolayers was observed, in particular by high subphase protein concentration. When the lipid films were subjected to oxidation stress by exposure to air, the surface properties of C-phycocyanin and dipalmitoylphosphatidylcholine were not greatly affected but the surface activity of monogalactosyldiacylglycerol was reduced dramatically by autoxidation. The oxidation of monogalactosyldiacylglycerol could not be prevented by the introduction of C-phycocyanin molecules at the lipid-water interface. 相似文献
2.
Methylation of the alpha 2(I) collagen gene in chemically transformed rat liver epithelial cells. 总被引:3,自引:0,他引:3 下载免费PDF全文
Phospholamban of isolated sarcoplasmic reticulum of cardiac and smooth muscle is phosphorylated by cyclic GMP-dependent protein kinase (G-kinase). Concomitantly, the affinity of the Ca2+ pump for Ca2+ is increased. These effects are very similar to those seen with cyclic AMP-dependent protein kinase (A-kinase). The phosphate incorporation into phospholamban and the stimulatory effects of both kinases on the Ca2+ pump are not additive, suggesting that G-kinase phosphorylates the same serine residue as A-kinase. A possible physiological role for phosphorylation of phospholamban by G-kinase is discussed. 相似文献
3.
Robert H. C. Chen Sabine Wislet-Gendebien Filsy Samuel Naomi P. Visanji Gang Zhang Diana Marsilio Tammy Langman Paul E. Fraser Anurag Tandon 《The Journal of biological chemistry》2013,288(11):7438-7449
α-Synuclein is an abundant presynaptic protein and a primary component of Lewy bodies in Parkinson disease. Although its pathogenic role remains unclear, in healthy nerve terminals α-synuclein undergoes a cycle of membrane binding and dissociation. An α-synuclein binding assay was used to screen for vesicle proteins involved in α-synuclein membrane interactions and showed that antibodies directed to the Ras-related GTPase Rab3a and its chaperone RabGDI abrogated α-synuclein membrane binding. Biochemical analyses, including density gradient sedimentation and co-immunoprecipitation, suggested that α-synuclein interacts with membrane-associated GTP-bound Rab3a but not to cytosolic GDP-Rab3a. Accumulation of membrane-bound α-synuclein was induced by the expression of a GTPase-deficient Rab3a mutant, by a dominant-negative GDP dissociation inhibitor mutant unable to recycle Rab3a off membranes, and by Hsp90 inhibitors, radicicol and geldanamycin, which are known to inhibit Rab3a dissociation from membranes. Thus, all treatments that inhibited Rab3a recycling also increased α-synuclein sequestration on intracellular membranes. Our results suggest that membrane-bound GTP-Rab3a stabilizes α-synuclein on synaptic vesicles and that the GDP dissociation inhibitor·Hsp90 complex that controls Rab3a membrane dissociation also regulates α-synuclein dissociation during synaptic activity. 相似文献
4.
Parmee ER He J Mastracchio A Edmondson SD Colwell L Eiermann G Feeney WP Habulihaz B He H Kilburn R Leiting B Lyons K Marsilio F Patel RA Petrov A Di Salvo J Wu JK Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2004,14(1):43-46
Substituted 4-amino cyclohexylglycine analogues were evaluated for DP-IV inhibitory properties. Bis-sulfonamide 15e was an extremely potent 2.6 nM inhibitor of the enzyme with excellent selectivity over all counterscreens. 2,4-difluorobenzenesulfonamide 15b and 1-naphthyl amide 16b, however, combined an acceptable in vitro profile with good pharmacokinetic properties in the rat, and 15b was orally efficacious at 3 mpk in an OGTT in lean mice. 相似文献
5.
Kowalchick JE Leiting B Pryor KD Marsilio F Wu JK He H Lyons KA Eiermann GJ Petrov A Scapin G Patel RA Thornberry NA Weber AE Kim D 《Bioorganic & medicinal chemistry letters》2007,17(21):5934-5939
Various beta-amino amides containing triazolopiperazine heterocycles have been prepared and evaluated as potent, selective, orally active dipeptidyl peptidase IV (DPP-4) inhibitors. These compounds display excellent oral bioavailability and good overall pharmacokinetic profiles in preclinical species. Moreover, in vivo efficacy in an oral glucose tolerance test in lean mice is demonstrated. 相似文献
6.
Xu J Wei L Mathvink R Edmondson SD Mastracchio A Eiermann GJ He H Leone JF Leiting B Lyons KA Marsilio F Patel RA Petrov A Wu JK Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2006,16(5):1346-1349
anti-Substituted beta-methylphenylalanine derived amides have been shown to be potent DPP-IV inhibitors exhibiting excellent selectivity over both DPP8 and DPP9. The optimized compound exhibited good pharmacokinetic profiles in three preclinical species. 相似文献
7.
Ciafardini G Marsilio V Lanza B Pozzi N 《Applied and environmental microbiology》1994,60(11):4142-4147
Oleuropein (Chemical Abstracts Service registry number 32619-42-4), a bitter-tasting secoiridoid glucoside commonly found in leaves of the olive tree as well as in olives (Olea europaea L.), was found to be hydrolyzed by the beta-glucosidase (EC 3.2.1.2.1) produced by oleuropeinolytic Lactobacillus plantarum-type strains. Three strains, designated B17, B20, and B21, were isolated from the brine of naturally ripe olives not treated with alkali. These strains were rod-shaped forms, grown at a pH 3.5 limit, and tolerated 1% oleuropein and 8% NaCl in the growth medium. The beta-glucosidase produced hydrolyzed 5-bromo-4-chloro-3-indolyl-beta-d-glucopy-ranoside as well as oleuropein. The presence of 2% glucose in the medium inhibited activity by 40 to 50%, depending on the bacterial strain. Chromatographic analysis of the trimethylsilyl derivatives of the products obtained after 7 days of incubation at 30 degrees C of strain B21 showed all the hydrolysis products of oleuropein, i.e., aglycone, iridoid monoterpen, and 3,4-dihydroxyphenylethanol (hydroxytyrosol). Oleuropein and its aglycone after 21 days of incubation decreased to trace levels with the simultaneous increase in concentration of beta-3,4-dihydroxyphenylethanol. 相似文献
8.
Xu J Ok HO Gonzalez EJ Colwell LF Habulihaz B He H Leiting B Lyons KA Marsilio F Patel RA Wu JK Thornberry NA Weber AE Parmee ER 《Bioorganic & medicinal chemistry letters》2004,14(18):4759-4762
Modification of in-house screening lead beta-aminoacyl proline 8 gave an equipotent thiazolidide 9. Extensive SAR studies on the phenyl ring of 9 led to the discovery of a novel series of potent and selective DP-IV inhibitors. Introduction of a fluorine at the 2-position proved to be crucial for the potency of this series. The 2,5-difluoro (22q) and 2,4,5-trifluoro (22t) analogues were potent inhibitors of DP-IV (IC(50)=270, 119nM, respectively). 相似文献
9.
Ashton WT Dong H Sisco RM Doss GA Leiting B Patel RA Wu JK Marsilio F Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2004,14(4):859-863
A diastereoselective synthesis was used to prepare a series of (3-substituted-cyclopentyl and -cyclohexyl)glycine pyrrolidides and thiazolidides. The three chiral centers were generated in an unambiguous, stereochemically defined manner. Inhibitory activity was dependent on the configuration at each stereocenter and on the nature of the 3-substituent. In the cyclopentylglycine pyrrolidide series, high potency against dipeptidyl peptidase IV and good selectivity could be achieved. 相似文献
10.
Xu J Wei L Mathvink R He J Park YJ He H Leiting B Lyons KA Marsilio F Patel RA Wu JK Thornberry NA Weber AE 《Bioorganic & medicinal chemistry letters》2005,15(10):2533-2536
anti-Substituted beta-methylphenylalanine derived amides have been shown to be potent DPP-IV inhibitors exhibiting excellent selectivity over both DPP8 and DPP9. These are among the most potent compounds reported to date lacking an electrophilic trap. The most potent compound among these is 5-oxo-1,2,4-oxadiazole 44, which is a 3 nM DPP-IV inhibitor. 相似文献