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1.
M A Rozenfel'd K B Gershkovich 《Izvestiia Akademii nauk SSSR. Seriia biologicheskaia》1989,(2):219-225
Generalized concepts of some structural peculiarities of fibrinogen, its transformation into fibrin and assembly have been considered on the basis of author's and published data. The role of local conformational changes in different areas of fibrinogen molecule and of separate reaction centers in formation of single- and double-stranded rod-like equilibrium fibrin oligomers and flexible branched copolymers of fibrinogen with fibrin E fragment has been considered. The mechanism of compactization has been discussed. 相似文献
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KB Cullberg T Christiansen SK Paulsen JM Bruun SB Pedersen B Richelsen 《Obesity (Silver Spring, Md.)》2013,21(3):454-460
Background:
Vascular growth is a prerequisite for adipose tissue (AT) development and expansion. Some AT cytokines and hormones have effects on vascular development, like vascular endothelial growth factor (VEGF‐A), angiopoietin (ANG‐1), ANG‐2 and angiopoietin‐like protein‐4 (ANGPTL‐4).Methods:
In this study, the independent and combined effects of diet‐induced weight loss and exercise on AT gene expression and proteins levels of those angiogenic factors were investigated. Seventy‐nine obese males and females were randomized to: 1. Exercise‐only (EXO; 12‐weeks exercise without diet‐restriction), 2. Hypocaloric diet (DIO; 8‐weeks very low energy diet (VLED) + 4‐weeks weight maintenance diet) and 3. Hypocaloric diet and exercise (DEX; 8‐weeks VLED + 4‐weeks weight maintenance diet combined with exercise throughout the 12 weeks). Blood samples and fat biopsies were taken before and after the intervention.Results:
Weight loss was 3.5 kg in the EXO group and 12.3 kg in the DIO and DEX groups. VEGF‐A protein was non‐significantly reduced in the weight loss groups. ANG‐1 protein levels were significantly reduced 22‐25% after all three interventions (P < 0.01). The ANG‐1/ANG‐2 ratio was also decreased in all three groups (P < 0.05) by 27‐38%. ANGPTL‐4 was increased in the EXO group (15%, P < 0.05) and 9% (P < 0.05) in the DIO group. VEGF‐A, ANG‐1, and ANGPTL‐4 were all expressed in human AT, but only ANGPTL‐4 was influenced by the interventions.Conclusions:
Our data show that serum VEGF‐A, ANG‐1, ANG‐2, and ANGPTL‐4 levels are influenced by weight changes, indicating the involvement of these factors in the obese state. Moreover, it was found that weight loss generally was associated with a reduced angiogenic activity in the circulation. 相似文献4.
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R.?B.?AisinaEmail author L.?I.?Mukhametova K.?B.?Gershkovich V.?N.?Yakovlev E.?I.?Goufman N.?B.?Tikhonova 《Russian Journal of Bioorganic Chemistry》2018,44(2):210-216
A method of ELISA for measuring the binding of different samples of immunoglobulin (IgG) and its fragments to human plasminogen (Pg) has been developed. Instead of plasminogen, the heavy chain of plasminogen (Pg-H) containing five ligand-binding kringle domains, immobilized on the surface of the plate, was used in this method as a detector. It was found that IgG treated with plasmin (IgGPm-t) binds to the immobilized Pg-H 2.84 times more strongly than intact IgG. Both IgG samples showed a weak nonspecific binding to the immobilized light chain of plasminogen (Pg-L). It was shown that 0.2 M L-lysine inhibits the binding of IgGPm-t and does not affect the nonspecific binding of intact IgG to the immobilized Pg-H, indicating the involvement of lysine-binding regions of Pg-H in binding to IgGPm-t. A preliminary treatment of IgG samples with carboxypeptidase В (CPB) inhibited the binding of IgGPm-t and did not affect the nonspecific binding of intact IgG to the immobilized Pg-H, which indicates a key role of the С-terminal lysine of IgGPm-t in the specific binding to the lysine-binding sites of Pg. The study of the effects of intact IgG and IgGPm-t on the rate of activation of Glu- and Lys-forms of Pg (Glu-Pg and Lys-Pg) by a tissue activator of Pg (tPA) and urokinase (uPA) in buffer showed that intact IgG completely inhibited the activation of Glu-Pg and Lys-Pg with both tPA and uPA. Presumably, the inhibitory effect of intact IgG is due to steric hindrances that it creates for protein–protein interactions of the activators with the zymogen. IgGPm-t accelerated the generation of plasmin from Pg. In this case, the stimulatory effect of IgGPm-t on the activation of Glu-Pg under the action of tPA was ~25% higher than on the activation of Lys-Pg, which is explained by more significant conformational changes in the Glu-Pg molecule compared with the Lys-Pg molecule after their binding to IgGPm-t. The results suggest that the specific cleavage of IgG by plasmin may be one of the ways by which the plasminogen/plasmin system is involved in various physiological and pathological processes. 相似文献
6.
R. B. Aisina L. I. Mukhametova D. A. Gulin M. Y. Levashov N. V. Prisyazhnaya K. B. Gershkovich S. D. Varfolomeyev 《Biochemistry. Biokhimii?a》2009,74(10):1104-1113
Angiostatins, kringle-containing fragments of plasminogen, are potent inhibitors of angiogenesis. Effects of three angiostatin
forms, K1–3, K1–4, and K1-4.5 (0–2 μM), on the rate of native Glu-plasminogen activation by its physiological activators in
the absence or presence of soluble fibrin were investigated in vitro. Angiostatins did not affect the intrinsic amidolytic activities of plasmin and plasminogen activators of tissue type (tPA)
and urokinase type (single-chain scuPA and two-chain tcuPA), but inhibited conversion of plasminogen to plasmin in a dose-dependent
manner. All three angiostatins suppressed Glu-plasminogen activation by tcuPA independently of the presence of fibrin, and
the inhibitory effect increased in the order: K1-3 < K1-4 < K1-4.5. The inhibitory effects of angiostatins on the scuPA activator
activity were lower and further decreased in the presence of fibrin. Angiostatin K1-3 (up to 2 μM) had no effect, while 2
μM angiostatins K1-4 and K1-4.5 inhibited the fibrin-stimulated Glu-plasminogen activation by tPA by 50 and 100%, respectively.
The difference in effects of the three angiostatins on the Glu-plasminogen activation by scuPA, tcuPA, and tPA in the absence
or presence of fibrin is due to the differences in angiostatin structures, mechanisms of action, and fibrin-specificity of
plasminogen activators, as well as due to the influence of fibrin on the Glu-plasminogen conformation. Angiostatins in vivo, which mimic plasminogen-binding activity, can inhibit plasminogen activation stimulated by various proteins (including fibrin)
of extracellular matrix, thereby blocking cell migration and angiogenesis. The data of this work indicate that the inhibition
of Glu-plasminogen activation under the action of physiological plasminogen activators by angiostatins can be implicated in
the complex mechanism of their antiangiogenic and antitumor action. 相似文献
7.
In this study we have produced for the first time a native fibrinogen copolymer with a fragment of fibrin E. and the molecular mechanism of its formation was studied by different physicochemical methods. Based on the data of angular dependency of the Debay scattering factor, the average molecular mass, coefficients of translational diffusion and the intrinsic viscosity it was shown that the primary interaction comprised the "end-to-end" fibrinogen dimerization through the D-D contacts with the following fragment E specific binding. It resulted in the stable three-domain D-E-D knot formation. The structural flexibility of the copolymer determines the tendency to their folding and the strong intermolecular hydrodynamic interaction indicates the structural compactization. This correlates as we think, with the presence of the centers of lateral binding in the fibrinogen molecule. Single-strand copolymers aggregate when they reach their critical sweep length resulting in microgel formation with the raise of the molecular mass. We came to the conclusion that fibrinogen molecules are capable to associate due to the stable native conformation shift into the active state, thus demasking the reaction groups in the D-domain. Possible reasons for the lack of fibrinogen heteropolymer rigidity characteristic for the fibrin polymers are discussed. 相似文献
8.
KB Gudmundsdóttir S Sigurdarson J Kristinsson T Eiríksson T Jóhannesson 《Acta veterinaria Scandinavica》2006,48(1):16-5
This study was undertaken in order to examine whether any connection existed between the amounts of iron in forage and the
sporadic occurrence of scrapie observed in certain parts of Iceland. As iron and manganese are considered antagonistic in
plants, calculation of the Fe/Mn ratios was also included by using results from Mn determination earlier performed in the
same samples. Forage samples (n = 170) from the summer harvests of 2001–2003, were collected from 47 farms for iron and manganese
analysis. The farms were divided into four categories: 1. Scrapie-free farms in scrapie-free areas (n = 9); 2. Scrapie-free farms in scrapie-afflicted areas (n = 17); 3. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 4. Scrapie-afflicted farms (n = 9). Farms in categories 1 and 2 are collectively referred to as scrapie-free farms. The mean iron concentration in forage samples from scrapie-afflicted farms was significantly higher than in forage samples
from farms in the other scrapie categories (P = 0.001). The mean Fe/Mn ratio in forage from scrapie-afflicted farms was significantly
higher than in forage from scrapie-free and scrapie-prone farms (P < 0.001). The results indicated relative dominance of iron
over manganese in forage from scrapie-afflicted farms as compared to farms in the other categories. Thus thorough knowledge
of iron, along with manganese, in soil and vegetation on sheep farms could be a pivot in studies on sporadic scrapie. 相似文献
9.
Scanning electron microscopy and gramicidin patch clamp recordings of microvillous receptor neurons dissociated from the rat vomeronasal organ 总被引:2,自引:1,他引:1
Vomeronasal organs from female rats were dissociated and isolated
microvillous receptor neurons were studied. The isolated receptor neurons
kept the typical bipolar shape which they have in situ as observed by
scanning electron microscopy. We applied the perforated patch-clamp
technique using the cation-selective ionophore gramicidin on freshly
isolated and well differentiated receptor neurons. The mean resting
potential was -58+/-14 mV (n=39). The contribution of the sodium pump
current to the resting potential was demonstrated by lowering the K+
concentration in the bath or by application of 100 microM dihydro-ouabain.
The input resistance was in the range of 1-6 GOmega and depolarizing
current pulses of a few pA were sufficient to trigger overshooting action
potentials. In voltage clamp conditions a fast transient sodium inward
current and a sustained outward potassium current were activated by
membrane depolarization. These observations indicate that freshly isolated
vomeronasal receptor neurons of rats can be recorded, using gramicidin,
with little modification of the intracellular content. Their
electrophysiological properties are very similar to those observed in situ.
Four out of eight female vomeronasal receptor cells were depolarized by
diluted rat male urine.
相似文献
10.
Gershkovich AA Verevka SV Kibirev VK Demchenko AP 《Journal of biochemical and biophysical methods》2000,45(2):183-191
A method of conjugating protein molecules under native conditions with water-insoluble hydrophobic compounds is developed. It permits very water-insoluble acids to be gently coupled to the primary amines on proteins or other biopolymers. For this purpose we synthesized a polymer (co-polymer of N-hydroxymaleimide and N-vinylpyrrolidone cross-linked by benzidine) which swells equally well in water and in organic solvents. Hydrophobic substances are first activated by esterification to this polymer in organic solvent and then conjugated to protein by acylation in aqueous medium at pH 8.0-8.5. Thus, the contact of native protein with organic co-solvent may be completely avoided. The application of this approach is demonstrated by labeling trypsinogen and plasminogen with dansyl proline. 相似文献