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排序方式: 共有209条查询结果,搜索用时 31 毫秒
51.
52.
Fiocco D Capozzi V Goffin P Hols P Spano G 《Applied microbiology and biotechnology》2007,77(4):909-915
The effect of overproducing each of the three small heat shock proteins (Hsp; Hsp 18.5, Hsp 18.55, and Hsp 19.3) was investigated
in Lactobacillus plantarum strain WCFS1. Overproduction of the three genes, hsp 18.5, hsp 18.55, and hsp 19.3, translationally fused to the start codon of the ldhL gene yielded a protein of approximately 19 kDa, as estimated from Tricine
sodium dodecyl sulfate–polyacrylamide gel electrophoresis in agreement with the predicted molecular weight of small Hsps.
Small Hsp overproduction alleviated the reduction in growth rate triggered by exposing exponentially growing cells to heat
shock (37 or 40°C) and cold shock (12°C). Moreover, overproduction of Hsp 18.55 and Hsp 19.3 led to an enhanced survival in
the presence of butanol (1% v/v) or ethanol (12% v/v) treatment suggesting a potential role of L. plantarum small Hsps in solvent tolerance. 相似文献
53.
Woo JH Hwang YO Kang SG Lee HS Cho JC Kim SJ 《Applied microbiology and biotechnology》2007,76(2):365-375
Previously, we reported that ten strains belonging to Erythrobacter showed epoxide hydrolase (EHase) activities toward various epoxide substrates. Three genes encoding putative EHases were
identified by analyzing open reading frames of Erythrobacter litoralis HTCC2594. Despite low similarities to reported EHases, the phylogenetic analysis of the three genes showed that eeh1 was similar to microsomal EHase, while eeh2 and eeh3 could be grouped with soluble EHases. The three EHase genes were cloned, and the recombinant proteins (rEEH1, rEEH2, and
rEEH3) were purified. The functionality of purified proteins was proved by hydrolytic activities toward styrene oxide. EEH1
preferentially hydrolyzed (R)-styrene oxide, whereas EEH3 preferred to hydrolyze (S)-styrene oxide, representing enantioselective hydrolysis of styrene oxide. On the other hand, EEH2 could hydrolyze (R)- and (S)-styrene oxide at an equal rate. The optimal pH and temperature for the EHases occurred largely at neutral pHs and 40–55
°C. The substrate selectivity of rEEH1, rEEH2, and rEEH3 toward various epoxide substrates were also investigated. This is
the first representation that a strict marine microorganism possessed three EHases with different enantioselectivity toward
styrene oxide. 相似文献
54.
Tsuyoshi Imai Mamiko Niwa Yusuke Ban Masashi Hirai Kazuko Ôba Takaya Moriguchi 《Plant Cell, Tissue and Organ Culture》2009,96(1):105-112
l-Galactono-1,4-lactone (GalL) dehydrogenase (GLDH) is an enzyme that catalyzes the last step of l-ascorbate (AsA) biosynthesis in plants. To re-evaluate the importance of the enzyme and the possibility of manipulating the
AsA content in plants, a cDNA encoding GLDH from sweet potato was introduced into tobacco plants by Agrobacterium-mediated transformation under the control of a CaMV 35S promoter. Protein blot analysis revealed the elevation of GLDH protein contents in three GLDH-transformed lines. Furthermore, these transgenic lines showed 6- to 10-fold higher GLDH activities in the roots than the
non-transformed plants, SR1. Despite the elevated GLDH activity, the AsA content in the leaves did not change in all lines;
i.e., the AsA content in GLDH-transformed lines was 3–7 μmol g−1 FW, comparable to that in the non-transformed plants. Incubation of leaf discs in a GalL solution led to a rapid 2- to 3-fold
increase in the AsA content in both GLDH-transformed and non-transformed plants in the same manner. These results suggest that the supply of GalL is a crucial factor
for determining the AsA pool size and that the upstream genes in the AsA biosynthetic pathway are responsible for enhancing
the AsA content in plants. 相似文献
55.
Breer K Girstun A Wielgus-Kutrowska B Staroń K Bzowska A 《Protein expression and purification》2008,61(2):122-130
Calf PNP is a ubiquitous enzyme of the salvage metabolic pathway. The procedure for this enzyme production in large quantities is described. The coding sequence of bovine PNP was amplified from the calf spleen cDNA library and was inserted into an expression vector pET28a(+). The construct was transformed into Escherichia coli BL21(DE3) strain. The protein expression efficiencies in the presence and the absence of IPTG were compared. It was found that IPTG is not necessary for obtaining a large quantity of recombinant calf PNP: 35 mg from 1 L cell culture. The enzyme was purified to 92% homogeneity by a two-step procedure consisting of gel filtration and ion exchange chromatography. The purity of recombinant enzyme is sufficient to form well diffracting single crystals.The basic kinetic parameters of recombinant PNP were determined and compared with the parameters of commercially available PNP from calf spleen. The specific activity in 50 mM phosphate buffer with inosine as a variable substrate (30.7 μmol min−1 mg−1) and other kinetic parameters: Michaelis constants, maximal velocities, dissociation and inhibition constants, determined for several typical PNP ligands, are similar to the values published previously for non-recombinant calf spleen PNP. As expected for mammalian PNP, recombinant calf PNP was found to have no substrate activity vs adenosine. The overexpression and purification method of the recombinant calf PNP provides significant amounts of the enzyme, which can successfully replace the non-recombinant PNP. 相似文献
56.
57.
Hemoglobin-binding proteins are necessary for pathogens to obtain iron from Hb. Entamoeba histolytica can grow using Hb as source of iron, but the underlying mechanism has not previously been established. In this work, we identified a 45 kDa Hb-binding protein of E. histolytica, which we named Ehhmbp45. In silico analysis showed that Ehhmbp45 contains the conserved domains needed for Hb-binding, while overlay assays demonstrated that Ehhmbp45 is able to bind Hb. In addition, we found that Ehhmbp45 mRNA levels were up-regulated under iron starvation conditions and were subsequently restored to basal levels when Hb was added to the cell cultures. These findings provide the first insights on the role of Ehhmbp45 in iron acquisition from Hb. 相似文献
58.
Active site modeling of dimerization interface in combination with site-directed mutagenesis indicates that the electron in the PrnD Rieske oxygenase can be transferred by either of two pathways, one involving Asp183′ and the other involving Asn180′. In addition, the overexpression of the isc operon involved in the assembly of iron-sulfur clusters increased the catalytic activity of PrnD in Escherichia coli by a factor of at least 4. 相似文献
59.
Wu X Itoh N Taniguchi T Hirano J Nakanishi T Tanaka K 《Biochemical and biophysical research communications》2004,317(4):1159-1164
Sodium-dependent vitamin C transporter (SVCT) 2 facilitates reduced ascorbic acid (AA) transport in MC3T3-E1 osteoblasts. Our previous studies suggested that Zn-induced osteoblast differentiation and Ca2+-, PO4(3-)-stimulated osteopontin (OPN) expression might result from their up-regulation effect on SVCT2 expression and AA uptake. Here, we investigated the role of SVCT2 on osteoblast differentiation by using SVCT2-overexpressing cells. Two clones of SVCT2-introduced cells overexpressed SVCT2 mRNA by 2.8- and 3.1-fold those of control cells, which resulted in obvious increase of AA uptake by 2.1- and 2.4-fold in Vmax with no change in Km. Alkaline phosphatase activity, hydroxyproline content significantly increased in SVCT2-overexpressing cells, and the induction of OPN mRNA was through up-regulation of OPN promoter activity by SVCT2 overexpression. Moreover, SVCT2-overexpressing cells exhibited more ability to promote mineralization and increase calcium deposition under the stimulation of 5 mM beta-glycerophosphate. These findings indicate that SVCT2 stimulates osteoblast differentiation and mineralization. 相似文献
60.
Michibata H Chiba H Wakimoto K Seishima M Kawasaki S Okubo K Mitsui H Torii H Imai Y 《Biochemical and biophysical research communications》2004,318(4):803-813
Psoriasis is recognized as a chronic inflammatory disease characterized by epidermal hyperproliferation. To identify psoriasis-related genes, we compared the mRNA populations of normal and psoriatic skin. We identified one gene, designated as cornifelin, which showed increased expression in psoriatic skin. Human cornifelin contains 112 amino acids and is expressed in the uterus, cervix, and skin. In situ hybridization analysis demonstrated the presence of human cornifelin in the granular cell layer of the epidermis. To investigate the function of cornifelin, we established a transgenic mouse line overexpressing human cornifelin. Using these mice, we have shown that cornifelin is directly or indirectly cross-linked to at least two other cornified envelope proteins, loricrin and involucrin, in vivo. Overexpression of human cornifelin correlated with decreased loricrin expression and increased involucrin expression in the transgenic mouse. However, abnormality of epidermal differentiation was not observed in the transgenic mouse. 相似文献