排序方式: 共有74条查询结果,搜索用时 15 毫秒
61.
Thrombi, which are dissolved primarily by plasmin (EC 3.4.21.7.), contain up to millimolar concentrations of fatty acids and these are known to affect the action of the protease. In the present study the modulation of plasmin activity was characterized quantitatively in a continuous amidolytic assay based on synthetic plasmin substrate (Spectrozyme-PL). A novel numerical procedure was applied for identification of kinetic parameters and their confidence intervals, with Monte Carlo simulation of the reaction progress curves, providing adequate grounds for discrimination of different models of the enzyme action. All three fatty acids caused a 10-20-fold increase in the Michaelis constant on Spectrozyme-PL (baseline value 5.9 mum). The catalytic constant decreased from 5.8.s(-1) to 2.4-2.8.s(-1) in the presence of arachidonate and oleate, but increased to 14.8.s(-1) in the presence of stearate, implying enhancement of plasmin activity at saturating substrate concentrations. However, based on the ratio of the catalytic and Michaelis constants, all three fatty acids acted as inhibitors of plasmin with various degrees of potency, showing concentration dependence in the range of 10-65 mum for oleate and arachidonate, and 115-230 mum for stearate. The reported effects of the three fatty acids require the presence of kringle 5 in the structure of the protease; miniplasmin (des-kringle 1-4 plasmin) is as sensitive to fatty acids as plasmin, whereas the activity of microplasmin (des-kringle 1-5 plasmin) is not affected. 相似文献
62.
Pasheva E Sarov M Bidjekov K Ugrinova I Sarg B Lindner H Pashev IG 《Biochemistry》2004,43(10):2935-2940
Histone acetyltransferases CBP, PCAF, and Tip60 have been tested for their ability to in vitro acetylate HMGB-1 and -2 proteins and their truncated forms lacking the C-terminal tail. It was found that these proteins were substrates for CBP only. Analyses of modified proteins by electrophoresis, amino acid sequencing, and mass spectrometry showed that full-length HMGB-1 and -2 were monoacetylated at Lys2. Removal of the C terminus resulted in (i) an increased incorporation of radiolabeled acetate within the proteins to a level close to that observed with histones H3/H4 and (ii) creation of a novel target site at Lys81. Acetylated and nonmodified HMGB-1 and -2 protein lacking the acidic tail were compared relative to their binding affinity to distorted DNA and the ability to bend linear DNA. Both proteins showed similar affinities to cisplatin-damaged DNA; the acetylated protein, however, was 3-fold more effective in inducing ligase-mediated circularization of a 111-bp DNA fragment. The alterations in the acetylation pattern of HMGB-1 and -2 upon removal of the C-terminal tail are regarded as a means by which the acidic domain modulates some properties of these proteins. 相似文献
63.
Melittin-induced changes in thylakoid membranes: particle electrophoresis and light scattering study
Doltchinkova V Georgieva K Traytcheva N Slavov C Mishev K 《Biophysical chemistry》2004,109(3):387-397
Thylakoids were used as a model system to evaluate the effect of bee venom peptide melittin (Mt) on membrane surface charge. At neutral pH, thylakoid membrane surfaces carry excess negative electrical charge. Mt strongly altered the electrophoretic mobility (EPM) of 'low-salt' thylakoids and did not significantly change the EPM of 'high-salt' thylakoids. Mt increased the primary ionic-exchange processes across the 'low-salt' thylakoid membranes, while it did not affect those of 'high-salt' thylakoids. Mt decreased the proton gradient generation on the membranes at both ionic strengths, but it affected more strongly the 'high-salt' than that of 'low-salt' thylakoids. The primary photochemical activity of photosystem II, estimated by the ratio Fv/Fm, was not influenced by the low Mt concentrations. It decreased only when chloroplasts had been incubated with higher Mt concentrations and this effect was better expressed in 'low-salt' than in 'high-salt' thylakoid membranes. 相似文献
64.
Irani NG Di Rubbo S Mylle E Van den Begin J Schneider-Pizoń J Hniliková J Šíša M Buyst D Vilarrasa-Blasi J Szatmári AM Van Damme D Mishev K Codreanu MC Kohout L Strnad M Caño-Delgado AI Friml J Madder A Russinova E 《Nature chemical biology》2012,8(6):583-589
Receptor-mediated endocytosis is an integral part of signal transduction as it mediates signal attenuation and provides spatial and temporal dimensions to signaling events. One of the best-studied leucine-rich repeat receptor-like kinases in plants, BRASSINOSTEROID INSENSITIVE 1 (BRI1), perceives its ligand, the brassinosteroid (BR) hormone, at the cell surface and is constitutively endocytosed. However, the importance of endocytosis for BR signaling remains unclear. Here we developed a bioactive, fluorescent BR analog, Alexa Fluor 647-castasterone (AFCS), and visualized the endocytosis of BRI1-AFCS complexes in living Arabidopsis thaliana cells. Impairment of endocytosis dependent on clathrin and the guanine nucleotide exchange factor for ARF GTPases (ARF-GEF) GNOM enhanced BR signaling by retaining active BRI1-ligand complexes at the plasma membrane. Increasing the trans-Golgi network/early endosome pool of BRI1-BR complexes did not affect BR signaling. Our findings provide what is to our knowledge the first visualization of receptor-ligand complexes in plants and reveal clathrin- and ARF-GEF-dependent endocytic regulation of BR signaling from the plasma membrane. 相似文献
65.
Hristov KL Parajuli SP Soder RP Cheng Q Rovner ES Petkov GV 《American journal of physiology. Cell physiology》2012,302(11):C1632-C1641
Overactive bladder syndrome is frequently associated with increased detrusor smooth muscle (DSM) contractility. We tested the hypothesis that pharmacological activation of the large-conductance voltage- and Ca(2+)-activated K(+) (BK) channel with NS-1619, a selective BK channel opener, reduces the excitability and contractility of human DSM. We used the amphotericin-perforated whole cell patch-clamp technique on freshly isolated human DSM cells, live-cell Ca(2+) imaging, and isometric DSM tension recordings of human DSM strips obtained from open bladder surgeries. NS-1619 (30 μM) significantly increased the amplitude of the voltage step-induced whole cell BK currents, and this effect was abolished by pretreatment with 200 nM iberiotoxin (IBTX), a selective BK channel inhibitor. In current-clamp mode, NS-1619 (30 μM) significantly hyperpolarized the resting membrane potential, and the hyperpolarization was reversed by IBTX (200 nM). NS-1619 (30 μM) significantly decreased the intracellular Ca(2+) level in isolated human DSM cells. BK channel activation with NS-1619 (30 μM) significantly inhibited the amplitude, muscle force, frequency, duration, and tone of the spontaneous phasic and pharmacologically induced DSM contractions from human DSM isolated strips. IBTX (200 nM) suppressed the inhibitory effects of NS-1619 on spontaneous contractions. The amplitude of electrical field stimulation (0.5-50 Hz)-induced contractions was significantly reduced by NS-1619 (30 μM). Our data suggest that pharmacological activation of BK channels could represent a novel treatment option to control bladder dysfunction in humans. 相似文献
66.
Maria Sporbert Helge Bruelheide Gunnar Seidler Petr Keil Ute Jandt Gunnar Austrheim Idoia Biurrun Juan Antonio Campos Andra arni Milan Chytrý Jnos Csiky Els De Bie Jürgen Dengler Valentin Golub John‐Arvid Grytnes Adrian Indreica Florian Jansen Martin Jirouek Jonathan Lenoir Miska Luoto Corrado Marcen Jesper Erenskjold Moeslund Aaron Prez‐Haase Solvita Rsia Vigdis Vandvik Kiril Vassilev Erik Welk 《植被学杂志》2019,30(4):620-632
67.
Viktoria Wagner Milan Chytrý Borja Jiménez‐Alfaro Jan Pergl Stephan Hennekens Idoia Biurrun Ilona Knollová Christian Berg Kiril Vassilev John S. Rodwell Željko Škvorc Ute Jandt Jörg Ewald Florian Jansen Ioannis Tsiripidis Zoltán Botta‐Dukát Laura Casella Fabio Attorre Valerijus Rašomavičius Renata Ćušterevska Joop H. J. Schaminée Jörg Brunet Jonathan Lenoir Jens‐Christian Svenning Zygmunt Kącki Mária Petrášová‐Šibíková Urban Šilc Itziar García‐Mijangos Juan Antonio Campos Federico Fernández‐González Thomas Wohlgemuth Viktor Onyshchenko Petr Pyšek 《Diversity & distributions》2017,23(9):969-981
68.
Kiril Chuchkov Radoslav Chayrov Anton Hinkov Daniel Todorov Kalina Shishkova Ivanka G. Stankova 《Nucleosides, nucleotides & nucleic acids》2020,39(7):979-990
АBSTRACTEsters of the antiherpetic drugs ganciclovir, penciclovir with the bile acids (cholic, chenodeoxycholic and deoxycholic) and amino acid esters of acyclovir were generated and evaluated for their in vitro antiviral activity against herpes simplex viruses type 1 and type 2 (HSV-1, HSV-2). The antiviral assays demonstrated that modified analogs of ACV and PCV are less active compared to the initial substances against HSV-1and HSV-2. CC50 for ganciclovir-deoxycholate corresponded to the CC50 of the other analogs and its activity is lower than ganciclovir. Obtained results show that tested modification do not improve bioavailability of nucleoside analogs in cells. 相似文献
69.
Brittney A. Otero Kiril Poukalov Ryan P. Hildebrandt Charles A. Thornton Kenji Jinnai Harutoshi Fujimura Takashi Kimura Katharine A. Hagerman Jacinda B. Sampson John W. Day Eric T. Wang 《Cell reports》2021,34(3):108634
- Download : Download high-res image (241KB)
- Download : Download full-size image
70.
Bank G. Fenyves Andreas Arnold Vaibhav G. Gharat Carmen Haab Kiril Tishinov Fabian Peter Dominique de Quervain Andreas Papassotiropoulos Attila Stetak 《Current biology : CB》2021,31(3):527-539.e7
- Download : Download high-res image (175KB)
- Download : Download full-size image