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31.
32.
M. Atta Noële Debaecker K. K. Andersson Jean-Marc Latour Lars Thelander Astrid Gräslund 《Journal of biological inorganic chemistry》1996,1(3):210-220
Mouse ribonucleotide reductase is composed of a 1?:?1 complex of two homodimeric subunits and catalyses the first unique step on the biochemical pathway to DNA synthesis. The small subunit, protein R2, contains dinuclear iron-oxygen clusters and a tyrosyl free radical required for catalytic activity. We have studied the mixed valent and fully reduced forms of the diiron oxygen cluster from mouse R2 protein by low-temperature EPR. EPR signals of the mixed-valent states of proteins R2 reconstituted with ferrous iron and oxygen in normal and deuterated water, using the same buffers, show apparent g values of 1.92, 1.73, and 1.60 for the mixed-valent state in H2O and 1.93, 1.73, and 1.62 in D2O. These g values are typical for diiron-oxygen proteins, while the effect of D2O is unprecedented for this class of proteins. We estimate the coupling constant J for the Heisenberg exchange (H?=?2J*S1*S2) to be J?=?–7.5±1?cm–1 for the mixed-valent form. The diferrous R2 protein shows an integer spin EPR signal in the presence of azide or 20% glycerol. Variable temperature variable field saturation magnetisation measurements show that only in the azide-complexed R2 protein does a weak ferromagnetic coupling occur (J?=?0.26±0.05?cm–1), while R2 protein in the absence or presence of 20% glycerol contains non-coupled mononuclear ferrous iron (S?=?2) sites. 相似文献
33.
Mariëtte P. C. van de Corput Roeland W. Dirks Wouter W. Wiegant Joop Wiegant Klaus Mühlegger A. K. Raap 《Histochemistry and cell biology》1997,108(4-5):359-364
Oestradiol has been conjugated to allylamine-dUTP with an 11-atom spacer to allow enzymatic incorporation of the label into
DNA sequences. In a comparative DNA and mRNA FISH study we have used DNA probes that were either labelled with digoxigenin,
biotin or oestradiol. Results show that oestradiol-labelled probes can detect DNA and RNA sequences in FISH equally well as
digoxigenin- and biotin-labelled probes. Further, no crossreactivity between the various hapten-specific antibodies and the
three haptens were observed. Binding of the rabbit anti-oestradiol antibody to endogenous oestrogen in various tissues was
not observed under the conditions tested. In view of the increasing demands for multi-colour DNA and mRNA FISH applications,
oestradiol is a welcome addition to the collection of haptens employed in FISH.
Accepted 20 June 1997 相似文献
34.
Phillip A Patten Russell J Howard Willem PC Stemmer 《Current opinion in biotechnology》1997,8(6):724-733
DNA shuffling is a practical process for directed molecular evolution which uses recombination to dramatically accelerate the rate at which one can evolve genes. Single and multigene traits that require many mutations for improved phenotypes can be evolved rapidly. DNA shuffling technology has been significantly enhanced in the past year, extending its range of applications to small molecule pharmaceuticals, pharmaceutical proteins, gene therapy vehicles and transgenes, vaccines and evolved viruses for vaccines, and laboratory animal models. 相似文献
35.
36.
Résumé Une candidose intestinale associée à une tumeur épithéliale, à métaplasie glandulaire, à pouvoir invasif marqué, provoquant une gêne du transit, a été découverte chez un Babouin de Guinée,Papio papio (Desm.) de la collection du Parc zoologique de Paris. A cette occasion nous avons rapporté les résultats concernant deux autres affections du tube digestid de nos Babouins captifs.
Report of a case of candidiasis of the digestive tract associated to an obstructive epithelial tumor, with great invasive ability, in a captive Baboon,Papio papio (Desm.). Included is a discussion of the incidence of some intestinal disturbances involving candidiasis of subhuman Primates.相似文献
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39.
Ruby Celeste Eugene Ackerman Laël C. Gatewood Clayton Reynolds George D. Molnar 《Bulletin of mathematical biology》1978,40(1):59-77
Mathematical models afford a procedure of unifying concepts and hypotheses by expressing quantitative relationships between
observables. The model presented indicates the roles of both insulin and glucagon as regulators of blood glucose, albeit in
different ranges of the blood glucose concentrations. Insulin secretion is induced during hyperglycemia, while glucagon secretion
results during hypoglycemia. These are demonstrated by simulations of a mathematical model conformed to data from the oral
glucose tolerance test and the insulin infusion test in normal control subjects and stable and unstable diabetic patients.
The model studies suggest the parameters could prove of value in quantifying the diabetic condition by indicating the degree
of instability.
Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976. 相似文献
40.
Françoise Phan-Dinh-Tuy Anne Weber Joëlle Henry Dominique Cottreau Axel Kahn 《Analytical biochemistry》1982,127(1):73-80
Electrophoresis on cellulose acetate strips was used to analyze protein kinases from normal rat liver. In addition to already well-characterized cAMP-dependent protein kinases type I and II and cAMP-independent casein kinases I and II, this method enabled the detection of several supplementary bands corresponding to kinases which were investigated according to their substrate specificity, activation by cAMP, and inhibition by the specific inhibitor of the catalytic subunit of cAMP-dependent protein kinases or by heparin. Using this rapid, sensitive, and resolutive electrophoretic method, different isozyme patterns could be obtained starting from minute amounts of different types of biological material. 相似文献