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1.
Herman Adlercreutz Yaghoob Mousavi Jim Clark Krister Hckerstedt Esa Hmlinen Kristiina Whl Taru Mkel Tapio Hase 《The Journal of steroid biochemistry and molecular biology》1992,41(3-8)
Thirty postmenopausal women (11 omnivores, 10 vegetarians and 9 apparently healthy women with surgically removed breast cancer) were investigated with regard to the association of their urinary excretion of estrogens, lignans and isoflavonoids (all diphenols) with plasma sex hormone binding globulin (SHBG). A statistically significant positive correlation between urinary total diphenol excretion and plasma SHBG was found which remained statistically significant after elimination of the confounding effect of body mass determined by body mass index (BMI). Furthermore we found a statistically significant negative correlation between plasma SHBG and urinary excretion of 16α-hydroxyestrone and estriol which also remained significant after eliminating the effect of BMI. Furthermore we observed that enterolactone (Enl) stimulates the synthesis of SHBG by HepG2 liver cancer cells in culture acting synergistically with estradiol and at physiological concentrations. Enl was rapidly conjugated by the liver cells, mainly to its monosulfate. Several lignans and the isoflavonoids daidzein and equol were found to compete with estradiol for binding to the rat uterine type II estrogen binding site (the s.c. bioflavonoid receptor). It is suggested that lignans and isoflavonoids may affect uptake and metabolism of sex hormones by participating in the regulation of plasma SHBG levels and in this way influence their biological activity and that they may inhibit cancer cell growth like some flavonoids by competing with estradiol for the type II estrogen binding sites. 相似文献
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Turunen P Jalkanen J Heikura T Puhakka H Karppi J Nyyssönen K Ylä-Herttuala S 《Journal of lipid research》2004,45(9):1633-1639
Oxidation of LDL generates biologically active platelet-activating factor (PAF)-like phospholipid derivatives, which have potent proinflammatory activity. These products are inactivated by lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme capable of hydrolyzing PAF-like phospholipids. In this study, we generated an adenovirus (Ad) encoding human Lp-PLA2 and injected 10(8), 10(9), and 10(10) plaque-forming unit doses of Adlp-PLA2 and control AdlacZ intra-arterially into rabbits to achieve overexpression of Lp-PLA2 in liver and in vivo production of Lp-PLA2-enriched LDL. As a result, LDL particles with 3-fold increased Lp-PLA2 activity were produced with the highest virus dose. Increased Lp-PLA2 activity in LDL particles decreased the degradation rate in RAW 264 macrophages after standard in vitro oxidation to 60-80% compared with LDL isolated from LacZ-transduced control rabbits. The decrease was proportional to the virus dose and Lp-PLA2 activity. Lipid accumulation and foam cell formation in RAW 264 macrophages were also decreased when incubated with oxidized LDL containing the highest Lp-PLA2 activity. Inhibition of the Lp-PLA2 activity in the LDL particles led to an increase in lipid accumulation and foam cell formation. It is concluded that increased Lp-PLA2 activity in LDL attenuates foam cell formation and decreases LDL oxidation and subsequent degradation in macrophages. 相似文献
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Paul Daly Mao Peng Hugh D. Mitchell Young-Mo Kim Charles Ansong Heather Brewer Peter de Gijsel Mary S. Lipton Lye Meng Markillie Carrie D. Nicora Galya Orr Ad Wiebenga Kristiina S. Hildén Mirjam A. Kabel Scott E. Baker Miia R. Mäkelä Ronald P. de Vries 《Environmental microbiology》2020,22(3):1154-1166
5.
Jenni Liisa Rahikainen James David Evans Saara Mikander Anna Kalliola Terhi Puranen Tarja Tamminen Kaisa Marjamaa Kristiina Kruus 《Enzyme and microbial technology》2013
Non-productive cellulase adsorption onto lignin is a major inhibitory mechanism preventing enzymatic hydrolysis of lignocellulosic feedstocks. Therefore, understanding of enzyme–lignin interactions is essential for the development of enzyme mixtures and processes for lignocellulose hydrolysis. We have studied cellulase–lignin interactions using model enzymes, Melanocarpus albomyces Cel45A endoglucanase (MaCel45A) and its fusions with native and mutated carbohydrate-binding modules (CBMs) from Trichoderma reesei Cel7A. Binding of MaCel45A to lignin was dependent on pH in the presence and absence of the CBM; at high pH, less enzyme bound to isolated lignins. Potentiometric titration of the lignin preparations showed that negatively charged groups were present in the lignin samples and that negative charge in the samples was increased with increasing pH. The results suggest that electrostatic interactions contributed to non-productive enzyme adsorption: Reduced enzyme binding at high pH was presumably due to repulsive electrostatic interactions between the enzymes and lignin. The CBM increased binding of MaCel45A to the isolated lignins only at high pH. Hydrophobic interactions are probably involved in CBM binding to lignin, because the same aromatic amino acids that are essential in CBM–cellulose interaction were also shown to contribute to lignin-binding. 相似文献
6.
Antti Nyyssölä Ville Pihlajaniemi Riikka Järvinen Saara Mikander Hanna Kontkanen Kristiina Kruus Heikki Kallio Johanna Buchert 《Enzyme and microbial technology》2013,52(4-5):272-278
Isolates from gardening waste compost and 38 culture collection microbes were grown on agar plates at pH 4.0 with the cutinase model substrate polycaprolactone as a carbon source. The strains showing polycaprolactone hydrolysis were cultivated in liquid at acidic pH and the cultivations were monitored by assaying the p-nitrophenyl butyrate esterase activities. Culture supernatants of four strains were analyzed for the hydrolysis of tritiated apple cutin at different pHs. Highest amounts of radioactive hydrolysis products were detected at pHs below 5. The hydrolysis of apple cutin by the culture supernatants at acidic pH was further confirmed by GC–MS analysis of the hydrolysis products. On the basis of screening, the acidic cutinase from Aspergillus niger CBS 513.88 was chosen for heterogeneous production in Pichia pastoris and for analysis of the effects of pH on activity and stability. The recombinant enzyme showed activity over a broad range of pHs with maximal activity between pH 5.0 and 6.5. Activity could be detected still at pH 3.5. 相似文献
7.
Kristiina Hildén Miia R. Mäkelä Taina Lundell Jaana Kuuskeri Alexey Chernykh Ludmila Golovleva David B. Archer Annele Hatakka 《Applied microbiology and biotechnology》2013,97(4):1589-1599
The lignin-degrading, biopulping white-rot fungus Physisporinus rivulosus secretes several laccases of distinct features such as thermostability, extremely low pH optima and thermal activation for oxidation of phenolic substrates. Here we describe the cloning, heterologous expression and structural and enzymatic characterisation of two previously undescribed P. rivulosus laccases. The laccase cDNAs were expressed in the methylotrophic yeast Pichia pastoris either with the native or with Saccharomyces cerevisiae α-factor signal peptide. The specific activity of rLac1 and rLac2 was 5 and 0.3 μkat/μg, respectively. However, mutation of the last amino acid in the rLac2 increased the specific laccase activity by over 50-fold. The recombinant rLac1 and rLac2 enzymes demonstrated low pH optima with both 2,6-dimethoxyphenol (2,6-DMP) and 2,2′-azino-bis(3-ethylbenzathiazoline-6-sulfonate). Both recombinant laccases showed moderate thermotolerance and thermal activation at +60 °C was detected with rLac1. By homology modelling, it was deduced that Lac1 and Lac2 enzymes demonstrate structural similarity with the Trametes versicolor and Trametes trogii laccase crystal structures. Comparison of the protein architecture at the reducing substrate-binding pocket near the T1-Cu site indicated the presence of five amino acid substitutions in the structural models of Lac1 and Lac2. These data add up to our previous reports on laccase production by P. rivulosus during biopulping and growth on Norway spruce. Heterologous expression of the novel Lac1 and Lac2 isoenzymes in P. pastoris enables the detailed study of their properties and the evaluation of their potential as oxidative biocatalysts for conversion of wood lignin, lignin-like compounds and soil-polluting xenobiotics. 相似文献
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Protein composition of 6K2‐induced membrane structures formed during Potato virus A infection
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The definition of the precise molecular composition of membranous replication compartments is a key to understanding the mechanisms of virus multiplication. Here, we set out to investigate the protein composition of the potyviral replication complexes. We purified the potyviral 6K2 protein‐induced membranous structures from Potato virus A (PVA)‐infected Nicotiana benthamiana plants. For this purpose, the 6K2 protein, which is the main inducer of potyviral membrane rearrangements, was expressed in fusion with an N‐terminal Twin‐Strep‐tag and Cerulean fluorescent protein (SC6K) from the infectious PVA cDNA. A non‐tagged Cerulean‐6K2 (C6K) virus and the SC6K protein alone in the absence of infection were used as controls. A purification scheme exploiting discontinuous sucrose gradient centrifugation followed by Strep‐tag‐based affinity chromatography was developed. Both (+)‐ and (–)‐strand PVA RNA and viral protein VPg were co‐purified specifically with the affinity tagged PVA‐SC6K. The purified samples, which contained individual vesicles and membrane clusters, were subjected to mass spectrometry analysis. Data analysis revealed that many of the detected viral and host proteins were either significantly enriched or fully specifically present in PVA‐SC6K samples when compared with the controls. Eight of eleven potyviral proteins were identified with high confidence from the purified membrane structures formed during PVA infection. Ribosomal proteins were identified from the 6K2‐induced membranes only in the presence of a replicating virus, reinforcing the tight coupling between replication and translation. A substantial number of proteins associating with chloroplasts and several host proteins previously linked with potyvirus replication complexes were co‐purified with PVA‐derived SC6K, supporting the conclusion that the host proteins identified in this study may have relevance in PVA replication. 相似文献
10.
Behrens Jane W. Ryberg Marie P. Einberg Heli Eschbaum Redik Florin Ann-Britt Grygiel Wlodzimierz Herrmann Jens Peter Huwer Bastian Hssy Karin Knospina Elina Nomaa Kristiina Oesterwind Daniel Polte Patrick Smoliski Szymon Ustups Didzis van Deurs Mikael Ojaveer Henn 《Biological invasions》2022,24(2):527-541
Biological Invasions - Native to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes... 相似文献