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61.
Performance characteristics of a reversible immunosensor with a heterobifunctional enzyme conjugate as signal generator 总被引:1,自引:0,他引:1
Factors that control the performance of a reversible immunosensor with an analyte (progesterone)-enzyme (horseradish peroxidase) conjugate as signal generator have been investigated. The conjugate is used in conjunction with two antibodies, which are specific to progesterone and to horseradish peroxidase, immobilized on two spatially separated polypropylene mesh discs. The conjugate and two antibodies are confined to an internal compartment of a microdialyzer by a semipermeable membrane. The small analyte from an external medium permeates across the membrane into the internal compartment where the analyte concentration determines the relative amounts of the bound conjugate on the two solid surfaces. By measuring two signals from the conjugate bound at two separate sites, we experimentally obtained time-response curves to a concentration pulse of the external analyte. A mathematical (kinetic) model describing the sensor system was developed and used for the determination of rate-limiting factors. In semicontinuous monitoring of the analyte concentrations, operation of the immunosensor with the enzyme conjugate as signal generator required special attention to (a) enzyme stability, (b) analyte permeation (dependence on medium components), and (c) kinetics related to the different accessibility to the same antibody of the small analyte (to be measured) vs. the larger counterpart on the enzyme conjugate (for signal generation). (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 221-231, 1997. 相似文献
62.
Endothelial STAT3 Activation Increases Vascular Leakage Through Downregulating Tight Junction Proteins: Implications for Diabetic Retinopathy 下载免费PDF全文
63.
Elena V. Popova Eun-Jung Lee Chun-Hua Wu Eun-Joo Hahn Kee-Yoeup Paek 《Plant Cell, Tissue and Organ Culture》2009,97(3):337-343
Two-years-old Ginkgo biloba cell culture initiated from cotyledonary explants was cryopreserved by a simple desiccation method. Preliminary incubation
of callus clumps on MS preculture medium supplemented with 100 g l−1 sucrose and 2 mg l−1 ABA for 7 and 14 days resulted in accumulation of endogenous soluble sugars and was essential for cell culture post-cryopreservation
survival. The optimal time for the preculture on sucrose-and-ABA containing medium was found to be 14 days. The sufficient
desiccation duration was determined as 150 min. FCM profiles of calli maintained for 2 years remained stable and were not
affected by cryopreservation. 相似文献
64.
65.
Soon-Yong Choi Hee Yun Park Aron Paek Gil Seob Kim Seong Eun Jeong 《Molecules and cells》2009,28(6):575-581
Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the biosynthesis of polyamines, which are essential for cell growth,
differentiation, and proliferation. This report presents the characterization of an ODC-encoding cDNA (SlitODC) isolated from
a moth species, the tobacco cutworm, Spodoptera litura (Lepidoptera); its expression in a polyamine-deficient strain of yeast, S. cerevisiae; and the recovery in polyamine levels and proliferation rate with the introduction of the insect enzyme. SlitODC encodes 448 amino acid residues, 4 amino acids longer than B. Mori ODC that has 71% identity, and has a longer C-terminus, consistent with B. mori ODC, than the reported dipteran enzymes. The null mutant yeast strain in the ODC gene, SPE1, showed remarkably depleted polyamine levels; in putrescine, spermidine, and spermine, the levels were > 7, > 1, and > 4%,
respectively, of the levels in the wild-type strain. This consequently caused a significant arrest in cell proliferation of
> 4% of the wild-type strain in polyaminefree media. The transformed strain, with the substituted SlitODC for the deleted endogenous ODC, grew and proliferated rapidly at even a higher rate than the wild-type strain. Furthermore,
its polyamine content was significantly higher than even that in the wild-type strain as well as the spe1-null mutant, particularly with a very continuously enhanced putrescine level, reflecting no inhibition mechanism operating
in the putrescine synthesis step by any corresponding insect ODC antizymes to SlitODC in this yeast system. 相似文献
66.
Boo-Ja Lee Sung-Kyu Kim Soo Bok Choi Ki-Jeong Kim Kyung-Hee Paek 《FEBS letters》2009,583(13):2315-917
Capsicum annuum L. Bugang exhibits a hypersensitive response against Tobacco mosaic virus (TMV) P0 infection. The C. annuumUDP-glucosyltransferase 1 (CaUGT1) gene was upregulated during resistance response to TMV and by salicylic acid, ethephon, methyl viologen, and sodium nitroprusside treatment. When the gene was downregulated by virus-induced gene silencing, a delayed HR was observed. In addition, free and total SA concentrations in the CaUGT1-downregulated hot pepper were decreased by 52% and 48% compared to that of the control plants, respectively. This suggested that the CaUGT1 gene was involved in resistance response against TMV infection by controlling the accumulation of SA. 相似文献
67.
The Haemophilus influenzae HMW1 adhesin is an important virulence exoprotein that is secreted via the two-partner secretion pathway and is glycosylated at multiple asparagine residues in consensus N-linked sequons. Unlike the heavily branched glycans found in eukaryotic N-linked glycoproteins, the modifying glycan structures in HMW1 are mono-hexoses or di-hexoses. Recent work demonstrated that the H. influenzae HMW1C protein is the glycosyltransferase responsible for transferring glucose and galactose to the acceptor sites of HMW1. An Actinobacillus pleuropneumoniae protein designated ApHMW1C shares high-level homology with HMW1C and has been assigned to the GT41 family, which otherwise contains only O-glycosyltransferases. In this study, we demonstrated that ApHMW1C has N-glycosyltransferase activity and is able to transfer glucose and galactose to known asparagine sites in HMW1. In addition, we found that ApHMW1C is able to complement a deficiency of HMW1C and mediate HMW1 glycosylation and adhesive activity in whole bacteria. Initial structure-function studies suggested that ApHMW1C consists of two domains, including a 15-kDa N-terminal domain and a 55-kDa C-terminal domain harboring glycosyltransferase activity. These findings suggest a new subfamily of HMW1C-like glycosyltransferases distinct from other GT41 family O-glycosyltransferases. 相似文献
68.
Taeyoung Kim Sukwon Kang Hyun Woo Kim Yee Paek Je Hoon Sung Young Hwa Kim Jae Kyung Jang 《Biotechnology and Bioprocess Engineering》2017,22(6):739-747
Microbial fuel cells (MFCs) degrade organic contaminants in wastewater while simultaneously producing electricity, but must be stacked to yield adequate voltage and current. This study examined the evolution of the chemical oxygen demand (COD) removal rate and efficiency in two identical individual MFCs (i-MFCs) in series- and parallel-connected stacks (sc- and pc-MFCs, respectively) under batch and continuous operation. The stack voltage and current increased in the respective series and parallel connections of the two i-MFCs (MFC unit 1 and MFC unit 2). Voltage reversal was observed in the sc- MFC below an external load of 100 Ω. Regardless of occurrence of the voltage reversal, organic reduction between i-MFCs and sc-MFCs showed no significant difference (gap of < 9% and < 6% in COD removal rate and efficiency, respectively); additionally, organic removals between the two individual MFCs in series indicated differences less than 9% of COD removal rate and 5% of COD removal efficiency in batch mode. Continuous operation also yielded similar organic removals as the MFCs in individual and series connection (voltage reversal occurred) mode, even over 8 days operation. Parallel connection yielded identical organic removals and currents in the two individual MFCs of the pc-MFC, even though the two separate i-MFCs showed different organic removal rates and current productions. This study provides the guide for the application of stacked MFCs for power source and efficient organic pollutant removal in wastewater treatment process. 相似文献
69.
70.
? In Cucumber mosaic virus (CMV) RNA replication, replicase-associated protein CMV 1a and RNA-dependent RNA polymerase protein CMV 2a are essential for formation of an active virus replicase complex on vacuolar membranes. ? To identify plant host factors involved in CMV replication, a yeast two-hybrid system was used with CMV 1a protein as bait. One of the candidate genes encoded Tsi1-interacting protein 1 (Tsip1), a zinc (Zn) finger protein. Tsip1 strongly interacted with CMV 2a protein, too. ? Formation of a Tsip1 complex involving CMV 1a or CMV 2a was confirmed in vitro and in planta. When 35S::Tsip1 tobacco (Nicotiana tabacum) plants were inoculated with CMV-Kor, disease symptom development was delayed and the accumulation of CMV RNAs and coat protein was decreased in both the infected local leaves and the uninfected upper leaves, compared with the wild type, whereas Tsip1-RNAi plants showed modestly but consistently increased CMV susceptibility. In a CMV replication assay, CMV RNA concentrations were reduced in the 35S::Tsip1 transgenic protoplasts compared with wild-type (WT) protoplasts. ? These results indicate that Tsip1 might directly control CMV multiplication in tobacco plants by formation of a complex with CMV 1a and CMV 2a. 相似文献