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91.
Sooyoun Seo Salwa Karboune Varoujan Yaylayan Lamia L’Hocine 《Process Biochemistry》2012,47(2):297-304
The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and potato galactan through the Maillard reaction, was investigated. The percent blocked lysine, estimated from the furosine content, reached a maximum value of 11.2% for LZM:galactan conjugates after 1 day incubation at a aw of 0.65. A maximum percent blocked lysine of 7.0 and 13.5% were obtained for LZM:galactose/GOS conjugates at a lower aw of 0.45 after 3 and 7 days, respectively. However, the low percent blocked lysine and the high protein aggregation index of LZM:galactose/GOS conjugates at aw 0.79 and 0.65 revealed the prevalence of the degradation of the Amadori compounds and the protein cross-linking. Mass spectrometry of LZM conjugates revealed the formation of different glycoforms. Glycated LZMs containing up to seven galactose moieties were formed; while only mono- and diglycated LZMs with GOSs were detected. 2–3 mol of galactan were conjugated to 1 mol of LZM. Response surface methodology, based on a 5-level and 3-factor central composite design, revealed that molar ratio and temperature were the most significant variables for the glycation of LZM with GOSs. The optimal conditions leading to a high percent blocked lysine (16.11%) with a low protein aggregation index (0.11) were identified: temperature of 49.5 °C, LZM:GOS molar ratio of 1:9 and aw of 0.65. To the best of our knowledge, this is the first study on the optimization of LZM glycation with GOSs. 相似文献
92.
Laïos I Journe F Laurent G Nonclercq D Toillon RA Seo HS Leclercq G 《The Journal of steroid biochemistry and molecular biology》2003,87(2-3):207-221
This study aimed at a better understanding of estrogen receptor alpha (ER) up regulation induced by partial estrogen antagonists. Effect of treatment with hydroxytamoxifen (OH-Tam) on ER level in MCF-7 cells was investigated by an approach combining ER measurement (enzyme immunoassay) and morphological demonstration (immunofluorescence). Furthermore, the influence of drug exposure on the rates of ER synthesis and degradation was assessed by determining [35S]methionine incorporated into the receptor in different experimental conditions (measurement of synthesis or pulse-chase experiments). ER up regulation was already induced by a 1-h pulse treatment with OH-Tam, thus a continuous exposure was not required. This process appeared reversible (i.e. ER accumulation due to OH-Tam rapidly vanished upon subsequent exposure to 17beta-estradiol (E2) or the pure antiestrogen RU 58668). While OH-Tam did not affect the rate of [35S]methionine incorporation into ER, it clearly caused an impairment of ER degradation (pulse-chase experiments) indicating that up regulation results from a stabilization of the receptor associated with the maintenance of its synthesis. Various tamoxifen derivatives, as well as a few related partial antiestrogens, were compared on the basis of binding ability and propensity to induce ER up regulation. A close relationship was found between both properties. Structure-activity analysis revealed that the capacity of these compounds to induce ER up regulation is associated with characteristics of their aminoalkyle side-chain, similar to those required for antiestrogenicity. 相似文献
93.
Seo Young Bang Jeong Hoon Kim Phil Young Lee Seung-Wook Chi Sayeon Cho Gwan-Su Yi Pyung Keun Myung Byoung Chul Park Kwang-Hee Bae Sung Goo Park 《Folia microbiologica》2013,58(5):403-408
In Saccharomyces cerevisiae, the Yap family of basic leucine zipper (bZip) proteins contains eight members. The Yap family proteins are implicated in a variety of stress responses; among these proteins, Yap1 acts as a major regulator of oxidative stress responses. However, the functional roles of the remaining Yap family members are poorly understood. To elucidate the function of Yap2, we mined candidate target genes of Yap2 by proteomic analysis. Among the identified genes, FRM2 was previously identified as a target gene of Yap2, which confirmed the validity of our screening method. YNL134C and YDL124W were also identified as candidate Yap2 target genes. These genes were upregulated in strains overexpressing Yap2 and possess Yap2 target sequences in their promoter regions. Furthermore, chromatin immunoprecipitation assays showed that YNL134C and YDL124W have Yap2 binding motif. These data will help to elucidate the functional role of Yap2. 相似文献
94.
The partial CaDSR6 (Capsicum annuum Drought Stress Responsive 6) cDNA was previously identified as a drought-induced gene in hot pepper root tissues. However, the cellular role of CaDSR6 with regard to drought stress tolerance was unknown. In this report, full-length CaDSR6 cDNA was isolated. The deduced CaDSR6 protein was composed of 234 amino acids and contained an approximately 30 amino acid-long Asp-rich domain in its central region. This Asp-rich domain was highly conserved in all plant DSR6 homologs identified and shared a sequence identity with the N-terminal regions of yeast p23fyp and human hTCTP, which contain Rab protein binding sites. Transgenic Arabidopsis plants overexpressing CaDSR6 (35S:CaDSR6-sGFP) were tolerant to high salinity, as identified by more vigorous root growth and higher levels of total chlorophyll than wild type plants. CaDSR6-overexpressors were also more tolerant to drought stress compared to wild type plants. The 35S:CaDSR6-sGFP leaves retained their water content and chlorophyll more efficiently than wild type leaves in response to dehydration stress. The expression of drought-induced marker genes, such as RD20, RD22, RD26, RD29A, RD29B, RAB18, KIN2, ABF3, and ABI5, was markedly increased in CaDSR6-overexpressing plants relative to wild type plants under both normal and drought conditions. These results suggest that overexpression of CaDSR6 is associated with increased levels of stress-induced genes, which, in turn, conferred a drought tolerant phenotype in transgenic Arabidopsis plants. Overall, our data suggest that CaDSR6 plays a positive role in the response to drought and salt stresses. 相似文献
95.
Young Rae Ji Hei Jung Kim Dong Hun Yu Ki Beom Bae Seo Jin Park Si Jun Park Woo Young Jang Min-Cheol Kang Jain Jeong Yong Hun Sung Minjee Choi Taejun Park Taesun Park Jong Won Yun Hyun-Shik Lee Sanggyu Lee Myoung Ok Kim Zae Young Ryoo 《Biochemical and biophysical research communications》2014
Chronic hepatitis is a major cause of liver cancer, so earlier treatment of hepatitis might be reducing liver cancer incidence. Hepatitis can be induced in mice by treatment with Concanavalin A (Con A); the resulting liver injury causes significant CD4+ T cell activation and infiltration. In these T cells, Roquin, a ring-type E3 ubiquitin ligase, is activated. To investigate the role of Roquin, we examined Con A-induced liver injury and T cell infiltration in transgenic (Tg) mice overexpressing Roquin specifically in T cells. In Roquin Tg mice, Con A treatment caused greater increases in both the levels of liver injury enzymes and liver tissue apoptosis, as revealed by TUNEL and H&E staining, than wild type (WT) mice. Further, Roquin Tg mice respond to Con A treatment with greater increases in the T cell population, particularly Th17 cells, though Treg cell counts are lower. Roquin overexpression also enhances increases in pro-inflammatory cytokines, including IFN-γ, TNF-α and IL-6, upon liver injury. Furthermore, Roquin regulates the immune response and apoptosis in Con A induced hepatitis via STATs, Bax and Bcl2. These findings suggest that over-expression of Roquin exacerbates T-cell mediated hepatitis. 相似文献
96.
Metabolic acids produced by oral pathogens demineralize tooth surfaces, leading to dental caries. Glucosyltransferases are the key factor in this process. We synthesized various modified oligosaccharides and tested them for their inhibitory effects on glucosyltransferase activity. Oligosaccharides were produced using a mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides and then further modified as iron- and sulfate-oligosaccharides. Iron- and sulfate-oligosaccharides reduced glucosyltransferase activity of Streptococci from 17% to 43% and prevented the formation of insoluble biomass on the surface of glass vials or stainless steel wires in the presence of sucrose. They also reduced the growth and acid productions of oral pathogens including S. mutans, S. sobrinus, Eikenella corrodens, Prevotella intermedia, and Actinobacillus actinomycetemcmitans. 相似文献
97.
Sun-Myung Bae Yong-Cheol Park Tae-Hee Lee Do-Hyun Kweon Jin-Ho Choi Sung-Koo Kim Yeon-Woo Ryu Jin-Ho Seo 《Enzyme and microbial technology》2004,35(6-7):545-549
Xylitol is a well-known sugar substitute with low-calorie and anti-cariogenic characteristics. An effort of biological production of xylitol from xylose was made in repeated fed-batch and cell-recycle fermentations of recombinant Saccharomyces cerevisiae BJ3505/δXR harboring the xylose reductase gene from Pichia stipitis. Batch fermentation with 20 g/l xylose and 18 g/l glucose resulted in 9.52 g/l dry cell mass, 20.1 g/l xylitol concentration and approximately 100% conversion yield. Repeated fed-batch operation to remove 10% of culture broth and to supplement an equal volume of 200 g/l xylose was designed to improve xylitol production. In spite of a sudden drop of cell concentration, an increase in dry cell mass led to high accumulation of xylitol at 48.7 g/l. To overcome loss of xylitol-producing biocatalysts in repeated fed-batch fermentation, cell-recycle equipment of hollow fiber membrane was implemented into a xylitol production system. Cell-recycle operation maintained concentration of the recombinant cells high inside a bioreactor. Final dry cell mass of 22.0 g/l, 116 g/l xylitol concentration, 2.34 g/l h overall xylitol productivity were obtained in cell-recycle fermentation supplemented with xylose and yeast extract solution, which were equivalent to 2.3-, 5.8- and 3.8-fold increases compared with the corresponding values of batch-type xylitol production parameters. 相似文献
98.
Heat shock proteins (HSPs) are rapidly induced by a variety of stressors, including heat shock, ethanol, heavy metals, UV, and gamma-radiation. Mitogen-activated protein kinases (MAPKs) are also involved in the stress transduction pathways in all eukaryotes. In this study, we attempted to determine whether radiofrequency (RF) radiation is able to induce a non-thermal stress response. Human T-lymphocyte Jurkat cells and rat primary astrocytes were exposed to 1763 MHz of RF radiation at an average specific absorption rate (SAR) of either 2 W/kg or 20 W/kg, for 30 min or 1 h. Temperature was completely controlled at 37 +/- 0.2 degrees C throughout the exposure period. The sham exposures were performed under exactly identical experimental conditions without exposure to RF radiation. We assessed alterations in the expression of HSPs and the activation of MAPKs in the RF-exposed cells. No detectable difference was observed in the expression levels of HSP90, HSP70, and HSP27. The phosphorylation status of MAPKs, extracellular signal-regulated kinases (ERK1/2), c-Jun N-terminal protein kinases (JNK1/2), or p38, did not change significantly. In order to determine whether RF radiation can promote the effects of 12-O-tetradecanoylphorbol 13-acetate (TPA) on stress response, cells were exposed to RF radiation coupled with TPA treatment. When TPA alone was applied, the MAPKs were found to be phosphorylated in a dose-dependent manner. However, RF radiation did not result in any enhancement of TPA-induced MAPK phosphorylation. Neither TPA nor RF radiation exerted any detectable effect on the induction of HSPs. These results indicate that 1763 MHz RF radiation alone did not elicit any stress response, nor did it have any effect on TPA-induced MAPK phosphorylation, under our experimental conditions. 相似文献
99.
Genetics of lagging strand DNA synthesis and maturation in fission yeast: suppression analysis links the Dna2-Cdc24 complex to DNA polymerase delta 下载免费PDF全文
The Cdc24 protein is essential for the completion of chromosomal DNA replication in fission yeast. Although its precise role in this process is unclear, Cdc24 forms a complex with Dna2, a conserved endonuclease–helicase implicated in the removal of the RNA–DNA primer during Okazaki fragment processing. To gain further insights into Cdc24–Dna2 function, we screened for chromosomal suppressors of the temperature-sensitive cdc24-M38 allele and mapped the suppressing mutations into six complementation groups. Two of these mutations defined genes encoding the Pol3 and Cdc27 subunits of DNA polymerase δ. Sequence analysis revealed that all the suppressing mutations in Cdc27 resulted in truncation of the protein and loss of sequences that included the conserved C-terminal PCNA binding motif, previously shown to play an important role in maximizing enzyme processivity in vitro. Deletion of this motif is shown to be sufficient for suppression of both cdc24-M38 and dna2-C2, a temperature-sensitive allele of dna2+, suggesting that disruption of the interaction between Cdc27 and PCNA renders the activity of the Cdc24–Dna2 complex dispensable. 相似文献
100.
Kim HJ Yun CY Cheon HM Chae B Lee IH Park SJ Kang YJ Seo SJ 《Archives of insect biochemistry and physiology》2004,56(1):21-33
We have sequenced a cDNA clone encoding a 26-kDa ferritin subunit, which was heavy chain homologue (HCH), in fall webworm, Hyphantria cunea. The HCH cDNA was obtained from the screening of a cDNA library using a PCR product. H. cunea ferritin is composed of 221 amino acid residues and their calculated mass is 26,160 Da. The protein contains the conserved motifs for the ferroxidase center typical for heavy chains of vertebrate ferritin. The iron-responsive element sequence with a predicted stem-loop structure is present in the 5'-untranslated region of ferritin HCH mRNA. The sequence alignment of ferritin HCH shows 68.9 and 68.7% identity with Galleria mellonella HCH (26 kDa ferritin) and Manduca sexta HCH, respectively. While G type insect ferritin vertebrate light chain homologue (LCH) is distantly related to H. cunea ferritin HCH (17.2-20.8%), the Northern blot analysis revealed that H. cunea ferritin HCH was ubiquitously expressed in various tissues and all developmental stages. The ferritin expression of midgut is more responsive to iron-fed, compared to fat body in H. cunea. 相似文献