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排序方式: 共有178条查询结果,搜索用时 140 毫秒
71.
De Vendittis E Castellano I Cotugno R Ruocco MR Raimo G Masullo M 《Journal of theoretical biology》2008,250(1):156-171
The growth temperature adaptation of six model proteins has been studied in 42 microorganisms belonging to eubacterial and archaeal kingdoms, covering optimum growth temperatures from 7 to 103 degrees C. The selected proteins include three elongation factors involved in translation, the enzymes glyceraldehyde-3-phosphate dehydrogenase and superoxide dismutase, the cell division protein FtsZ. The common strategy of protein adaptation from cold to hot environments implies the occurrence of small changes in the amino acid composition, without altering the overall structure of the macromolecule. These continuous adjustments were investigated through parameters related to the amino acid composition of each protein. The average value per residue of mass, volume and accessible surface area allowed an evaluation of the usage of bulky residues, whereas the average hydrophobicity reflected that of hydrophobic residues. The specific proportion of bulky and hydrophobic residues in each protein almost linearly increased with the temperature of the host microorganism. This finding agrees with the structural and functional properties exhibited by proteins in differently adapted sources, thus explaining the great compactness or the high flexibility exhibited by (hyper)thermophilic or psychrophilic proteins, respectively. Indeed, heat-adapted proteins incline toward the usage of heavier-size and more hydrophobic residues with respect to mesophiles, whereas the cold-adapted macromolecules show the opposite behavior with a certain preference for smaller-size and less hydrophobic residues. An investigation on the different increase of bulky residues along with the growth temperature observed in the six model proteins suggests the relevance of the possible different role and/or structure organization played by protein domains. The significance of the linear correlations between growth temperature and parameters related to the amino acid composition improved when the analysis was collectively carried out on all model proteins. 相似文献
72.
Vincenza Rita Lo Vasco Martina Leopizzi Valeria Di Maio Tania Di Raimo Stefania Cesa Alessandra Masci Carlo Della Rocca 《Journal of cell communication and signaling》2017,11(4):317-327
Endothelial cells (EC) act as leading actors in angiogenesis. Understanding the complex network of signal transduction pathways which regulate angiogenesis might offer insights in the regulation of normal and pathological events, including tumours, vascular, inflammatory and immune diseases. The effects of olive oil and of Blueberry extracts upon the phosphoinositide (PI)-specific phospholipase C (PLC) enzymes were evaluated both in quiescent and inflammatory stimulated human umbilical vein EC (HUVEC) using molecular biology (multiliquid bioanalysis) and immunofluorescence techniques. Oleuropein significantly increased the number of surviving HUVEC compared to untreated controls, suggesting that it favours the survival and proliferation of EC. Our results suggest that Oleuropein might be useful to induce EC proliferation, an important event during angiogenesis, with special regard to wound healing. Blueberry extracts increased the number of surviving HUVEC, although the comparison to untreated controls did not result statistically significant. Lipopolysaccharide (LPS) administration significantly reduced the number of live HUVEC. LPS can also modify the expression of selected PLC genes. Adding Blueberry extracts to LPS treated HUVEC cultures did not significantly modify the variations of PLC expression induced by LPS. Oleuropein increased or reduced the expression of PLC genes, and statistically significant results were identified for selected PLC isoforms. Oleuropein also modified the effects of LPS upon PLC genes’ expression. Thus, our results corroborate the hypothesis that Oleuropein owns anti-inflammatory activity. The intracellular localization of PLC enzymes was modified by the different treatments we used. Podosome-like structures were observed in differently LPS treated HUVEC. 相似文献
73.
Katsuyuki Kusuzaki Takao Matsubara Hiroaki Murata Mariantonia Logozzi Elisabetta Iessi Rossella Di Raimo 《Journal of enzyme inhibition and medicinal chemistry》2017,32(1):908-916
Photodynamic molecules represent an alternative approach for cancer therapy for their property (i) to be photo-reactive; (ii) to be not-toxic for target cells in absence of light; (iii) to accumulate specifically into tumour tissues; (iv) to be activable by a light beam only at the tumour site and (v) to exert cytotoxic activity against tumour cells. However, to date their clinical use is limited by the side effects elicited by systemic administration. Extracellular vesicles are endogenous nanosized-carriers that have been recently introduced as a natural delivery system for therapeutic molecules. We have recently shown the ability of human exosomes to deliver photodynamic molecules. Therefore, this review focussed on extracellular vesicles as a novel strategy for the delivery of photodynamic molecules at cancer sites. This completely new approach may enhance the delivery and decrease the toxicity of photodynamic molecules, therefore, represent the future for photodynamic therapy for cancer treatment. 相似文献
74.
Michael K. McMillian Pearlie M. Hudson Harold H. Suh Hong Ye Raimo K. Tuominen John S. Hong 《Journal of neurochemistry》1993,61(1):93-99
Abstract: The relative contributions of Ca2+ influx and intracellular Ca2+ mobilization were examined for angiotensin II-stimulated [3 H]phorbol 12, 13-dibutyrate binding, which reflects the level of activated protein kinase C in bovine chromaffin cells. Angiotensin II receptors activate phospholipase C in chromaffin cells, leading to a shortlived mobilization of intracellular Ca2+ . Angiotensin II-stimulated [3 H]phorbol 12, 13-dibutyrate binding was largely blocked in Ca2+ -free buffer and by pretreatment with the Ca2+ -channel blocker ω-conotoxin GVIA. The [3 H]phorbol 12, 13-dibutyrate binding response to [Sar1 ]angiotensin II also appeared to be voltage sensitive, as no additivity was observed with the response to the depolarizing agent 4-aminopyridine (3 m M ). Threshold sensitivities of the extra-and intracellular Ca2+ -mobilizing pathways to angiotensin II were similar, and all examined effects of angiotensin II in these cells were apparently mediated by losartan-sensitive (AT1 -Iike) receptors. The dependence of angiotensin II-stimulated [3 H]phorbol 12, 13-dibutyrate binding on extracellular Ca2+ entry, in contrast to stimulation by other phospholipase C-linked receptor agonists (bradykinin and methacholine), suggests that angiotensin II preferentially stimulates protein kinase C translocation to the plasma membrane, rather than to internal membranes, in bovine adrenal medullary cells. 相似文献
75.
Riikka Heikinheimo Harri Hemilä Raimo Pakkanen Ilkka Palva 《Applied microbiology and biotechnology》1991,35(1):51-55
Summary The gene coding for pectin methylesterase (PME) of Erwinia chrysanthemi B374 (pme) was cloned by a polymerase chain reaction. The pme gene was expressed in Bacillus subtilis using a secretion vector based on the promoter and signal sequence of the -amylase gene from B. amyloliquefaciens. The cultivation of B. subtilis cells carrying the cloned pme resulted in efficient secretion of PME into the culture medium based on enzymatic and sodium dodecyl sulphate-polyacrylamide gel electrophoresis characterizations. The NH2-terminal sequence analysis of the secreted PME revealed two different NH2-termini. Heterologous processing was probably due to a second putative signal peptidase cleavage site at the joint region between the PME and -amylase signal peptide.
Offprint requests to: R. Heikinheimo 相似文献
76.
D-alanine oxidase from Escherichia coli: participation in the oxidation of L-alanine 总被引:2,自引:1,他引:1
Cell wall-membrane preparations of Escherichia coli, prepared by the ethylenediaminetetraacetic acid-lysozyme method, contain enzymes which catalyze the oxidation of d-alanine and, to a lesser extent, l-alanine into pyruvate and ammonia without the formation of hydrogen peroxide. The kinetic parameters were (i) pH optima of 8.3 to 8.4 for l- and d-alanine and (ii) a K(m) value of 6.6 +/- 0.2 mM for d-alanine. Several coenzymes were without effect when added to the reaction mixture. The participation of d-alanine oxidase in the oxidation of l-alanine was demonstrated. The evidence is based on (i) results of cellular fractionation; (ii) labeling experiments; (iii) inhibition studies with aminooxyacetate and cycloserine; (iv) denaturation experiments; and (v) demonstration of the presence of an active racemase. 相似文献
77.
D-alanine oxidase form Escherichia coli: localization and induction by L-alanine 总被引:3,自引:0,他引:3
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Dialyzed membranes of Escherichia coli prepared by an ethylenediaminetetraacetic acid-lysozyme method catalyze the oxidation of both l-alanine and d-alanine. The specific activities for the oxidations of both d-alanine and l-alanine are increased fivefold when the cells are grown in the presence of either l-alanine or dl-alanine, but are increased only slightly when grown in the presence of d-alanine. In the dl-alanine-induced system, the specific activities for the oxidations of some other d-amino acids are also raised. dl-alanine also induces two other alanine catabolizing enzymes, alanine dehydrogenase and alanine-glutamate aminotransferase which are found in the "soluble" fraction of lysozyme-treated cells. The oxidations of both l-alanine and d-alanine were associated with the membranes of induced cells. After the membranes were disintegrated by sonic treatment, both l-alanine and d-alanine oxidation catalysts sedimented in a sucrose density gradient together with d-lactate and l-lactate dehydrogenases, apparently as a single multienzyme complex. 相似文献
78.
Gypsy mothLymantria dispar L. larvae were exposed toApanteles melanoscelus (Ratzeburg) females contaminated with nuclear polyhedrosis virus. Three methods of contamination (ovipositor, total body surface, and exposure to infected hosts) and two exposure periods (2 and 24 hours) were tested. A significantly greater incidence of larval mortality caused by virus occurred among larvae exposed to contaminated than among larvae exposed to uncontaminated parasites for 2 and 24 hours. No significant differences occurred in larval mortality caused by virus for the 3 methods of contamination for the 2- and 24-hour tests or in parasite emergence from larvae parasitized by contaminated or uncontaminated parasites. 相似文献
79.
Lindén J Korkalainen M Lensu S Tuomisto J Pohjanvirta R 《Journal of biochemical and molecular toxicology》2005,19(3):139-148
An acutely toxic dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) leads to a drastically and permanently reduced feed intake and wasting by an unknown mechanism. We focused on the possible interference of TCDD with hypothalamic factors known to take part in the regulation of eating and metabolism, utilizing the over 1000-fold TCDD-sensitivity difference between Long-Evans (Turku/AB; L-E) and Han/Wistar (Kuopio) rats. The mRNA expression of 18 hypothalamic factors (including NPY, AgRP, and CART) was measured by quantitative RT-PCR at 6, 24 and 96 h after TCDD administration. The effects of TCDD were compared with those of leptin and with feed restriction employing a TCDD dose that elicited a severe reduction of feed intake in L-E rats. TCDD mainly modified expression of orexigenic factors causing an initial suppression followed by reversal to enhanced expression by 96 h. The latter was also seen in feed-restricted controls. In contrast, leptin altered both orexigenic and anorexigenic factor mRNAs in a more even manner and its effects were clustered at 6 h. The transient nature of feeding-promoting factor suppression does not strongly support a key role for this phenomenon in TCDD-induced wasting syndrome. However, the fact that TCDD mainly affected orexigenic factors and the temporal differences in response found between the rat strains warrant further research. 相似文献
80.