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1.
2.
In-vitro-grown cells of Mucuna pruriens, immobilized in calcium-alginate gels, were able to transform the precursor L-tyrosine into L-dihydroxyphenylalanine (L-DOPA). After the immobilization in alginate the plant cells released 90% of the produced L-DOPA into the medium; supplementation of the medium with calcium inhibited both the transformation of L-tyrosine into L-DOPA and the release of L-DOPA into the medium. Continuous illumination of the beads had a slight beneficial effect on the synthesis of L-DOPA. A simple production medium for the transformation of L-tyrosine into L-DOPA was designed. This medium contained only sucrose and sodium chloride as osmotic stabilizers, a low concentration of calcium chloride for stabilization of the alginate beads, and L-tyrosine as the precursor. 相似文献
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Walter Harm 《Molecular & general genetics : MGG》1960,91(1):52-62
Summary The inactivation of phage T4 by nitrous acid (HNO2) is essentially an exponential function of time of treatment. HNO2-inactivated T4 is able to undergo multiplicity reactivation, and genetic markers may be rescued by live phage, however, the extent of both effects is appreciably less than after UV-inactivation. Also, the survival of phenotypic function of the cistronsr II-A andr II-B is lower with HNO2-treatment than with a UV-irradiation of a corresponding number of hits.The reduced effects are quantitatively accounted for by the assumption of lethal hits blocking early steps of infection. These early-step damages amount to approximately 1/6 of the total hit number; it is still unknown whether they occur in DNA or in protein. Some indication for the occurrence in protein comes from the result that the host-killing efficiency of HNO2-inactivated phage is reduced at a similar rate as these early-step damages occur. However, at least 5/6 of the lethal hits are due to chemical changes within the DNA, as can be calculated from the results of multiplicity reactivation, marker rescue, and phenotypic survival of therII-cistrons.
Mit 6 Textabbildungen 相似文献
Mit 6 Textabbildungen 相似文献
5.
Emile CL. Marnette Harm Houweling Herman Van Dam Jan Willem Erisman 《Biogeochemistry》1993,23(2):119-144
The chemical composition of surface waters of two Dutch moorland pools and of incident precipitation, was monitored from 1982
to 1990. For this period, sulfur and water budgets were calculated using a hydrochemical model developed for well-mixed non-stratifying
lakes. Total atmospheric deposition of S decreased significantly after 1986 at both locations. A model describing the sulfur
budget in terms of input, output and reduction/oxidation processes predicted a fast decrease of pool water SO4
2− concentrations after a decrease of atmospheric input. However, SO4
2− concentrations in the surface water was lowered only slightly or remained constant. Apparently a source within the lake caused
the unexpectedly high SO4
2− concentrations. The possible supply of SO4
2− from the sediment through regulation by (K-)Al-SO4 containing minerals or desorption of SO4
2− from positively charged surfaces in the sediment was evaluated. Solubility calculations of pore water with respect to alunite,
basaluminite and jurbanite indicated that SO4
2− concentration was not regulated by these minerals. It is suggested here (1) that desorption of SO4
2− from peaty sediments may account for the estimated SO4
2− supply provided that the adsorption complex is periodically recharged by partial oxidation of the upper bottom sediments
and (2) that because of exposure of a part of the pool bottom to the atmosphere during dry summers and subsequent oxidation
of reduced S, the amount of SO4
2− may be provided which complements the decreasing depositional SO4
2− input. In future research these two mechanisms need to be investigated. 相似文献
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From cells of Mucuna pruriens, grown in suspension, a monophenol monooxygenase (EC 1.14.18.1) was purified to homogeneity, as deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme appeared to have a native molecular weight of 90000±5000 dalton, and consisted of two subunits, each of 42000±1000 dalton. High-performance liquid chromatography with electrochemical detection for specific measurement of catecholes, was used to determine separately the tyrosinehydroxylating and catecholase activities of the enzyme. For the enzymatic activities, pH optima of, respectively, 7.5 and 5.5–6.5 were found; the effects of some inhibitors on both activities appeared to be different. Michaelis-Menten characteristics for some mono-and o-dihydroxysubstrates were determined.Abbreviations DEAE
diethylaminoethyl
- HPLC
high-performance liquid chromatography
- L-DOPA
L-3,4-dihydroxyphenylalanine 相似文献
8.
Adaptation to Cadmium by Klebsiella aerogenes Growing in Continuous Culture Proceeds Mainly via Formation of Cadmium Sulfide 总被引:9,自引:7,他引:2 下载免费PDF全文
Harry Aiking Karin Kok Harm van Heerikhuizen Jan van 't Riet 《Applied microbiology》1982,44(4):938-944
The adaptation of Klebsiella aerogenes to high levels of cadmium was studied in continuous culture under conditions of glucose limitation. When up to 6 × 10−4 M cadmium was added to a culture in steady state, growth ceased instantaneously but resumed within 5 h (dilution rate, 0.1 h−1). When again in steady state, these adapted cells exhibited a far greater tolerance to cadmium than did unadapted cells (not previously exposed to cadmium) when tested on solid media containing different concentrations of cadmium. This relative insensitivity of adapted cells to cadmium was subsequently lost in continuous culture within 5 days after omitting cadmium from the influent medium. Thus, the phenomenon was an inducible physiological process. Adapted cells contained substantial amounts of cadmium (up to 2.4% of the bacterial dry weight). The cadmium content of the cells was dependent on growth conditions and was found to be proportional to the inorganic sulfide content of the cells in all cases. This suggested that formation of CdS is probably the most important mechanism of detoxification in this organism. The presence of large numbers of electron-dense granules on the cell surface (absent in cultures without added cadmium) provided additional support for this conclusion. 相似文献
9.
10.
Fabrizio Chiodo Marco Marradi Boris Tefsen Harm Snippe Irma van Die Soledad Penadés 《PloS one》2013,8(8)
Improved detection of anti-carbohydrate antibodies is a need in clinical identification of biomarkers for cancer cells or pathogens. Here, we report a new ELISA approach for the detection of specific immunoglobulins (IgGs) against carbohydrates. Two nanometer gold glyconanoparticles bearing oligosaccharide epitopes of HIV or Streptococcus pneumoniae were used as antigens to coat ELISA-plates. A ~3,000-fold improved detection of specific IgGs in mice immunized against S. pneumoniae respect to the well known BSA-glycoconjugate ELISA was achieved. Moreover, these multivalent glyconanoparticles have been employed in solid phase assays to detect the carbohydrate-dependent binding of human dendritic cells and the lectin DC-SIGN. Multivalent glyconanoparticles in ELISA provide a versatile, easy and highly sensitive method to detect and quantify the binding of glycan to proteins and to facilitate the identification of biomarkers. 相似文献