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81.
Enhanced therapeutic importance of recombinant human granulocyte colony stimulating factor (rhG-CSF) has encouraged us to
develop a processing method for its high-level expression in E. coli. In this study, we established a high-yielding clone by incorporation of silent mutations at N-terminal region of human G-CSF
gene. We studied and optimized various parameters of culture conditions connected with the expression of rhG-CSF. The maximum
expression was obtained in a defined medium supplemented with 1% glucose. The gene in pET-3a vector in E. coli BL21 (DE3) PLysS host strain was induced with 2 mM isopropyl β-d-1-thiogalacto pyronoside. The cell growth and productivity was enhanced about 1.6- and 1.5-folds, respectively when inducing
the culture at OD600 value of 6 than 2. The protein expression was significantly increased by addition of rifampicin at concentration of 200 μg/ml.
The AT content of 51.8% with suitable codon sequences at N-terminal region and the concentration of rifampicin were identified
as the key factors with a significant impact on protein expression. The specific productivity of 104 mg/OD/l (68.7% of total
cellular protein) of rhG-CSF was obtained toward the end of the study, which is almost 1.5 times higher yield than reported
so far in the literature. 相似文献
82.
83.
ATP plays a significant role in the function of molecular chaperones of the large heat shock protein families. However, its role in the functions of chaperones of the small heat shock protein families is not understood very well. We report here a study on the role of ATP on the structure and function of the major eye lens chaperone alpha-crystallin. Our in vitro study shows that at physiological temperature, ATP induces the association of alpha-crystallin with substrate proteins. The association process is reversible and low affinity in nature with unit binding stoichiometry. 4,4'-Dianilino-1,1'-binaphthyl-5,5-disulfonic acid, dipotassium salt, binding studies show that ATP induces the exposure of additional hydrophobic sites on alpha-crystallin, but no appreciable enhancement of the same was observed for the substrate protein gamma-crystallin or carbonic anhydrase. An equilibrium unfolding study reveals that ATP at 3 mgm concentration stabilizes the alpha-crystallin structure by 4.5 kJ/mol. The compactness induced by ATP makes it more resistant to tryptic cleavage. ATP-induced association of chaperone alpha-crystallin with substrate enhanced its aggregation prevention ability and also enhanced the refolding yield of lactate dehydrogenase from the unfolded state. Our results suggest that the binding of ATP to alpha-crystallin and not its hydrolysis is required for all these effects, as replacement of ATP by its nonhydrolyzable analogue adenosine-5'-O-(3-thiotriphosphate), tetralithium salt, reproduced all the results faithfully. The implication of the ATP-induced reversible protein-protein association at physiological temperatures on the functional role of alpha-crystallin in vivo is discussed. 相似文献
84.
The mode and nature of the binding of chlorpromazine (CPZ), a psychotropic drug, with milk proteins – -lactalbumin (with substantial amounts of -helix, -sheet and random coil), -lactoglobulin (a major -sheeted protein) and s-casein (a random coiled protein) have been studied spectrofluorometrically and spectropolarimetrically. The binding affinity of CPZ for unfolded proteins is comparatively less than that of folded proteins although the number of binding sites is smaller in the latter case, due to the greater extent of binding of CPZ for folded proteins. Thermodynamic analysis reveals that CPZ binds to -lactalbumin and s-casein in an endothermic (Ho is positive) and hydrophobic manner but with -lactoglobulin in an exothermic (Ho is negative) manner. Far UV Circular dichroic studies reveal that CPZ increases the secondary structure of the major -sheeted protein, -lactoglobulin possibly by increasing the relative contact orders (non-local contacts) within the residues. On the other hand, for proteins possessing random coil, it increases the unfolded state of the protein. CPZ does not affect local contacts in a-helix when its interaction is compared with a major -helical protein, myoglobin. 相似文献
85.
Radoslaw Panczak Marcel Zwahlen Adrian Spoerri Kali Tal Martin Killias Matthias Egger for the Swiss National Cohort 《PloS one》2013,8(1)
Background
Homicide–suicides are rare but catastrophic events. This study examined the epidemiology of homicide-suicide in Switzerland.Methods
The study identified homicide–suicide events 1991–2008 in persons from the same household in the Swiss National Cohort, which links census and mortality records. The analysis examined the association of the risk of dying in a homicide–suicide event with socio-demographic variables, measured at the individual-level, household composition variables and area-level variables. Proportional hazards regression models were calculated for male perpetrators and female victims. Results are presented as age-adjusted hazard ratios (HR) with 95% confidence intervals (95%CI).Results
The study identified 158 deaths from homicide–suicide events, including 85 murder victims (62 women, 4 men, 19 children and adolescents) and 68 male and 5 female perpetrators. The incidence was 3 events per million households and year. Firearms were the most prominent method for both homicides and suicides. The risk of perpetrating homicide-suicide was higher in divorced than in married men (HR 3.64; 95%CI 1.56–8.49), in foreigners without permanent residency compared to Swiss citizens (HR 3.95; 1.52–10.2), higher in men without religious affiliations than in Catholics (HR 2.23; 1.14–4.36) and higher in crowded households (HR 4.85; 1.72–13.6 comparing ≥2 with <1 persons/room). There was no association with education, occupation or nationality, the number of children, the language region or degree of urbanicity. Associations were similar for female victims.Conclusions
This national longitudinal study shows that living conditions associated with psychological stress and lower levels of social support are associated with homicide-suicide events in Switzerland. 相似文献86.
87.
88.
Scott Pitnick Kali R. H. Henn Stephen D. Maheux Dawn M. Higginson Jorge L. Hurtado-Gonzales Mollie K. Manier Kirstin S. Berben Chase Guptill J. Albert C. Uy 《Proceedings. Biological sciences / The Royal Society》2009,276(1671):3229-3237
Whenever males can monopolize females and/or resources used by females, the opportunity for sexual selection will be great. The greater the variation among males in reproductive success, the greater the intensity of selection on less competitive males to gain matings through alternative tactics. In the yellow dung fly, Scathophaga stercoraria, males aggressively compete for access to receptive, gravid females on fresh dung. Larger males are better able to acquire mates and to complete copulation successfully and guard the female throughout oviposition. Here we demonstrate that when an alternative resource is present where females aggregate (i.e. apple pomace, where both sexes come to feed), smaller males will redirect their searching for females from dung to the new substrate. In addition, we identify a class of particularly small males on the alternative substrate that appears never to be present searching for females on or around dung. Smaller males were found to have a mating ‘advantage’ on pomace, in striking contrast to the pattern observed on dung, providing further support for the existence of an alternative male reproductive tactic in this species. 相似文献
89.
Boris Lakatoš Barbora Kaliňaková Daniela Hudecová Ľudovít Varečka 《Central European Journal of Biology》2010,5(2):143-150
The thiazol dye Thioflavin T (ThT), which is used to stain amyloid fibrils, was found to have strong inhibitory effects on
both growth and conidiation of the deuteromycete Trichoderma viride at concentrations between 10–100 μg/ml (ca. 30–300 μmol/l). Thioflavin S (ThS), also known to stain amyloid fibrils, had no significant effect at these concentrations.
Both stains yielded a fluorescence response, but their distributions were different. ThT was non-homogenously distributed
throughout the cytoplasm, whereas ThS fluorescence was strongly bound to septal regions. The effect of ThT was studied on
several model microorganisms. It exerted a strong inhibitory effect on Staphylococcus aureus (Gram-positive bacterium) (MIC=10 μmol/l), but the effect on Escherichia coli (Gram-negative bacterium) was one order of magnitude less pronounced. The effect on Candida albicans was also very strong (MIC=50 μmol/l). The dermatophytic fungus Microsporum gypseum and deuteromycete Alternaria alternata were less affected by ThT (MIC=250 μmol/l and >500 μmol/l, respectively). These results show that ThT could be a useful inhibitor
of selected microorganisms, whereas ThS could be a useful agent for monitoring formation and maintenance of intrahyphal septa
without inhibiting the growth of the microorganism. 相似文献
90.
A. Paige Adams Roberto Navarro-Lopez Francisco J. Ramirez-Aguilar Irene Lopez-Gonzalez Grace Leal Jose M. Flores-Mayorga Amelia P. A. Travassos da Rosa Kali D. Saxton-Shaw Amber J. Singh Erin M. Borland Ann M. Powers Robert B. Tesh Scott C. Weaver Jose G. Estrada-Franco 《PLoS neglected tropical diseases》2012,6(11)