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81.
M Nakazato S Morozumi K Saito K Fujinuma T Nishima N Kasai 《Applied and environmental microbiology》1990,56(5):1465-1470
Four fungal strains, namely, Aspergillus niger, Eurotium herbariorum, a Rhizopus sp., and non-aflatoxin (AF)-producing Aspergillus flavus, which could convert AF-B1 to aflatoxicol (AFL), could also reconvert AFL to AF-B1. The interconversion of AF-B1 to AFL and of AFL to AF-B1 was ascertained to occur during proliferation of the fungi. These reactions were distinctly observed in cell-free systems obtained from disrupted mycelia of A. flavus and the Rhizopus sp., but they were not observed in culture filtrates from intact (nondisrupted) mycelia of the same strains. The interconversion activities of AF-B1 and AFL were not observed when the cell-free systems were preheated at 100 degrees C. These findings strongly suggest that the interconversion of AF-B1 and AFL is mediated by intracellular enzymes of A. flavus and the Rhizopus sp. In addition, the isomerization of AFL-A to AFL-B observed in culture medium was also found to occur by the lowering of the culture pH. 相似文献
82.
Y Tatsumi K Asonuma S Uemoto K Tanaka K Ozawa K Satouchi K Saito 《Life sciences》1989,44(15):1053-1058
Changes in phospholipids and their fatty acid composition in liver mitochondria obtained from allogenic rats with orthotopic liver transplants were measured with and without immunosuppressive treatment. In untreated allogenic rats, mitochondrial phosphorylation activity was severely deteriorated at 8 days after transplantation. A significant change was also found in the amount of cardiolipin compared with other classes of phospholipids. Namely, cardiolipin decreased, and lysodiphosphatidylglycerol and phosphatidylglycerol increased concomitantly. Furthermore, the percentage of linoleic acid in cardiolipin decreased dramatically. Decrease in cardiolipin and changes in its fatty acid composition may be attributed to the deterioration of mitochondrial function upon acute rejection. 相似文献
83.
Gene expression and immunohistochemical localization of basic fibroblast growth factor in renal cell carcinoma. 总被引:2,自引:0,他引:2
J Eguchi K Nomata S Kanda T Igawa M Taide S Koga F Matsuya H Kanetake Y Saito 《Biochemical and biophysical research communications》1992,183(3):937-944
Renal cell carcinoma is known as a neoplastic condition of renal tubular cells and usually shows a hypervascular tumor in angiographic examination. We examined the presence of basic fibroblast growth factor (bFGF) in human renal cell carcinoma. To determine if alterations in bFGF gene expression are present in human renal cell carcinoma, paired samples of normal and neoplastic renal tissue from 6 patients were analyzed for bFGF mRNA content by Northern blot hybridization. In 4 out of 6 patients, tumor tissue expressed bFGF mRNA 2 to 4 times greater than corresponding normal tissue. Two patients showed minimal elevation of tumor bFGF mRNA. The localization of bFGF in the renal cell carcinoma tissue was also examined using immunohistochemical staining, and it was found that bFGF was positively stained at the nuclei of tumor cells and the cell surface. These results suggest that increased expression of bFGF may be associated with neoplastic growth in renal tubular epithelial cells and neovascularization. 相似文献
84.
Y Ohyama K Miyamoto Y Saito N Minamino K Kangawa H Matsuo 《Biochemical and biophysical research communications》1992,183(2):743-749
Two similar membrane bound guanylate cyclases (GC-A and GC-B) are known as natriuretic peptide receptors, but have not been well characterized yet. In this study, we have isolated two forms of GC-B cDNA clones along with GC-A cDNA clones from rat brain. The two forms of rat GC-B differ from each other only by 75bp deletion at 3'-flanking region of the putative transmembrane domain, the shorter form lacking the nucleotide binding site by the deletion. Expression of these cDNAs on mammalian cells revealed that (1) GC-B is a specific receptor for CNP whereas GC-A is stimulated effectively both by ANP and BNP, and (2) the two forms of GC-B possess practically the same high binding affinity for CNP while the shorter form could not induce cGMP production by the binding of CNP. These data indicate that in rat brain is present the non-functional receptor for CNP caused by the short deletion. 相似文献
85.
M Shiozaki R Sakai M Tabuchi M Shinohara M Kosaka S Saito Y Eto 《Biochemical and biophysical research communications》1992,183(1):273-279
Activin A/EDF, initially found as a differentiation inducer of murine Friend erythroleukemia, also has a stimulatory effect on erythropoiesis in vitro and in vivo. Here we proved activin A/EDF activity in human serum. The activin A/EDF level in 18 normal human serum samples was measured by a specific bioassay and was found to be 8.3 +/- 4.6 ng/ml, indicating that there exists sufficient activity to affect erythropoiesis in normal serum. In contrast, activin A/EDF activity was reduced in the chronic renal failure patients and 23/26 serum samples examined showed levels below 1.2 ng/ml. Further analysis using HPLC revealed that chronic renal failure serum actually contained as much activin A/EDF as normal serum, and that the difference between normal and patient serum existed in the content of a specific inhibitor of activin A/EDF. This observation suggests the possibility that the inhibitor is participating in the regulation of activin A/EDF activity in vivo in chronic renal failure patients and also the possibility of activin A/EDF could be utilized in the therapy of the anemia of such patients. 相似文献
86.
H Cho S E Ramer M Itoh E Kitas W Bannwarth P Burn H Saito C T Walsh 《Biochemistry》1992,31(1):133-138
The cytoplasmic domains of two human transmembrane protein tyrosine phosphatases (PTPases), LAR and CD45, have been expressed in Escherichia coli, purified to near-homogeneity, and compared for catalytic efficiency toward several phosphotyrosine-containing peptide substrates. A 615-residue LAR fragment (LAR-D1D2) containing both tandemly repeated PTPase domains shows almost identical specific activity and high catalytic efficiency as the 40-kDa single-domain LAR-D1 fragment, consistent with a single functional active site in the 70-kDa LAR-D1D2 enzyme. A 90-kDa fragment of the human leukocyte CD45 PTPase, containing two similar tandemly repeated PTPase domains, shows parallel specificity to LAR-D1 and LAR-D1D2 with a high kcat/Km value for a phosphotyrosyl undecapeptide. Sufficient purified LAR-D1 and LAR-D1D2 PTPases were available to demonstrate enzymatic exchange of 18O from 18O4 inorganic phosphate into H2(16)O at rates of approximately 1 x 10(-2) s-1. The oxygen-18 exchange probably proceeds via a phosphoenzyme intermediate. Brief incubation of all three PTPase fragments with a [32P]phosphotyrosyl peptide substrate prior to quench with SDS sample buffer and gel electrophoresis led to autoradiographic detection of 32P-labeled enzymes. Pulse/chase studies on the LAR 32P-enzyme showed turnover of the labeled phosphoryl group. 相似文献
87.
Three-dimensional solution structure of the B domain of staphylococcal protein A: comparisons of the solution and crystal structures. 总被引:6,自引:0,他引:6
The three-dimensional solution structure of the recombinant B domain (FB) of staphylococcal protein A, which specifically binds to the Fc portion of immunoglobulin G, was determined by NMR spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. On the basis of 692 experimental constraints including 587 distance constraints obtained from the nuclear Overhauser effect (NOE), 57 torsion angle (phi, chi 1) constraints, and 48 constraints associated with 24 hydrogen bonds, a total of 10 converged structures of FB were obtained. The atomic root mean square difference among the 10 converged structures is 0.52 +/- 0.10 A for the backbone atoms and 0.98 +/- 0.08 A for all heavy atoms (excluding the N-terminal segment from Thr1 to Glu9 and the C-terminal segment from Gln56 to Ala60, which are partially disordered). FB is composed of a bundle of three alpha-helices, i.e., helix I (Gln10-His19), helix II (Glu25-Asp37), and helix III (Ser42-Ala55). Helix II and helix III are antiparallel to each other, whereas the long axis of helix I is tilted at an angle of about 30 degrees with respect to those of helix II and helix III. Most of the hydrophobic residues of FB are buried in the interior of the bundle of the three helices. It is suggested that the buried hydrophobic residues form a hydrophobic core, contributing to the stability of FB.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
88.
Ochiai Hiroshi; Hata Katsusuke; Saito Tamao; Funamoto Satoru; Nakata Nobuyuki 《Plant & cell physiology》1996,37(2):135-139
The cellular slime mold, Polysphondylium pallidum, has two EDTA-resistanttypes of cell-cell adhesion. The major component of them hasbeen identified as a glycoprotein with a molecular mass of 64kDa on SDS-PAGE (referred to as gp64). We found that a substantialamount of the gp64 run as dimer, when gp64 was dissolved inSDS-sample buffer without 2-mercaptoethanol and then subjectedto electrophoresis. The occurrence of a homophilic dimer wasdemonstrated by analyzing the dimer-like band on a gel for itsamino acid sequence and amino acid composition. The dimer-likeband also was analyzed by three sorts of monoclonal antibodies,two of which recognize respectively a conforniational epitopeand a denatured epitope of the protein moiety of gp64. The dataindicate that the native conformation of gp64 is necessary fordimer formation.
2Present address: Institute of Immunological Science, HokkaidoUniversity, Sapporo, 060 Japan 相似文献
89.
Although in vitro studies have shown that oxygen free radicals depress the sarcolemmal Ca2+-pump activity and thereby may cause the occurrence of intracellular Ca2+ overload for the genesis of contractile failure, the exact relationship between changes in sarcolemmal Ca2+-pump activity and cardiac function due to these radicals is not clear. In this study we examined the effects of oxygen radicals on sarcolemmal Ca2+ uptake and Ca2+-stimulated ATPase activities as well as contractile force development by employing isolated rat heart preparations. When hearts were perfused with medium containing xanthine plus xanthine oxidase, the sarcolemmal Ca2+-stimulated ATPase activity and ATP-dependent Ca2+ accumulation were depressed within 1 min whereas the developed contractile force, rate of contraction and rate of relaxation were increased at 1 min and decreased over 3–20 min of perfusion. The resting tension started increasing at 2 min of perfusion with xanthine plus xanthine oxidase. Catalase showed protective effects against these alterations in heart function and sarcolemmal Ca2+-pump activities upon perfusion with xanthine plus xanthine oxidase whereas superoxide dismutase did not exert such effects. The combination of catalase and superoxide dismutase did not produce greater effects in comparison to catalase alone. These results are consistent with the view that the depression of heart sarcolemmal Ca2+ pump activities may result in myocardial dysfunction due to the formation of hydrogen peroxide and/or hydroxyl radicals upon perfusing the hearts with xanthine plus xanthine oxidase. 相似文献
90.
Tohru Tsukui Sanae Miyake Sadahiro Azuma Hirotake Ichise Izumu Saito Yutaka Toyoda 《Molecular reproduction and development》1995,42(3):291-297
Replication-defective recombinant adenovirus, Adex4SRLacZL, was used as a vector for transferring exogenous genes in mouse zona pellucida-free eggs at the pronuclear stage. The vector contained the E. coli LacZ reporter gene under the control of the SRα promoter (SV40 early promoter-fused HTLV-I LTR), and the expression of the reporter gene was examined during preimplantation development in culture. Histochemical staining of the embryos for β-galactosidase activity showed that the exogenous LacZ gene as expressed in 98% of the embryos at the morula-blastocyst stages. As in the microinjection method, the exogenous genes could be pursued from the 2-cell stage. Neither apparent morphological changes nor cytotoxic effects were observed. Both the percentages of embryos expressing reporter genes and the rate of development to the blastocyst stage were higher in the adenovirus vector-treated embryos than in the microinjected ones. These results suggest that the adenovirus vector system is a useful tool in investigating the genetic control of early mammalian development. © 1995 wiley-Liss, Inc. 相似文献