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81.
Differentiation of lactic streptococcal phages into phage species by DNA-DNA homology. 总被引:18,自引:10,他引:8 下载免费PDF全文
A W Jarvis 《Applied microbiology》1984,47(2):343-349
Twenty-five lactic streptococcal bacteriophages were differentiated by DNA homology into four species. Complete correlation was found between DNA homology groups and morphological characteristics of the phages except that two phage types, which differed in only the presence or absence of a collar, were one species by DNA homology. These findings were supported by serological data and differences in DNA molecular weights of the proposed species. The complete lack of homology between these phage species indicates that they are unlikely to have a recent common phage ancestor and that one morphological type of phage has not been derived by mutation from a phage of another morphological type. 相似文献
82.
Christer Jansson Örjan Hansson Hans-Erik Åkerlund Lars-Erik Andreasson 《Biochemical and biophysical research communications》1984,124(1):269-276
EPR measurements on inside-out thylakoids revealed that salt-washing, known to inhibit oxygen evolution and release a 23 and a 16 kDa protein, induced a Signal IIf and decreased the EPR signal from state S2. Readdition of the released 23 kDa protein restored the oxygen evolution and decreased the Signal IIf, but did not relieve the decrease in the state S2 signal. It is suggested that salt-washing inhibits the electron transfer from the oxygen-evolving site to Z, the physiological donor to P680. In inhibited photosystem II units lacking Signal IIf, Z+ is rapidly reduced, possibly by a modified S-cycle unable to evolve oxygen. 相似文献
83.
Transformation of leukotriene A4 methyl ester to leukotriene C4 monomethyl ester by cytosolic rat glutathione transferases 总被引:6,自引:0,他引:6
Bengt Mannervik Helgi Jensson Per Ålin Lars Örning Sven Hammarström 《FEBS letters》1984,175(2):289-293
Six major basic cytosolic glutathione transferases from rat liver catalyzed the conversion of leukotriene A4 methyl ester to the corresponding leukotriene C4 monomethyl ester. Glutathione transferase 4-4, the most active among these enzymes, had a Vmax of 615 nmol X min-1 X mg protein-1 at 30 degrees C in the presence of 5 mM glutathione. It was followed in efficiency by transferase 3-4 which had a Vmax of 160 nmol X min-1 X mg-1 under the same conditions. Transferases 1-1, 1-2, 2-2 and 3-3 had at least 30 times lower Vmax values than transferase 4-4. 相似文献
84.
Inside-out thylakoid membrane vesicles can be isolated by aqueous polymer two-phase partition of Yeda press-fragmented spinach chloroplasts (Andersson, B. and Åkerlund, H.-E. (1978) Biochim. Biophys. Acta 503, 462–472). The mechanism for their formation has been investigated by studying the yield of inside-out vesicles after various treatments of the chloroplasts prior to fragmentation. No inside-out vesicles were isolated during phase partitioning if the chloroplasts had been destacked in a low-salt medium prior to the fragmentation. Only in those cases where the chloroplast lamellae had been stacked by cations or membrane-paired by acidic treatment did we get any yield of inside-out vesicles. Thus, the intrinsic properties of chloroplast thylakoids seem to be such that they seal into right-side out vesicles after disruption unless they are in an appressed state. This favours the following mechanism for the formation of inside-out thylakoids. After press treatment, a ruptured membrane still remains appressed with an adjacent membrane. Resealing of such an appressed membrane pair would result in an inside-out vesicle.If the compartmentation of chloroplast lamellae into appressed grana and unappressed stroma lamellae is preserved by cations before fragmentation, the inside-out vesicles are highly enriched in photosystem II. This indicates a granal origin which is consistent with the proposed model outlined. Inside-out vesicles possessing photosystem I and II properties in approximately equal proportions could be obtained by acid-induced membrane-pairing of chloroplasts which had been destacked and randomized prior to fragmentation. Since this new preparation of inside-out thylakoid vesicles also exposes components derived from the stroma lamellae it complements the previous preparation.It is suggested that fragmentation of paired membranes followed by phase partitioning should be a general method of obtaining inside-out vesicles from membranes of various biological sources. 相似文献
85.
R. Brändén T. Nilsson S. Styring J. Ångström 《Biochemical and biophysical research communications》1980,92(4):1306-1312
Preparations of RuBP carboxylase are shown to carry out an oxygen dependent decarboxylation of L-3-phosphoglyceric acid. The product of this reaction is probably phosphoglycollate. L-3-phosphoglyceric acid, formed by RuBP carboxylase is therefore proposed to be the primary substrate for photorespiration. 相似文献
86.
Lars-Åke Fransson Anders Malmström Ingrid Sjöberg Thomas N. Huckerby 《Carbohydrate research》1980,80(1):131-145
Heparin, heparan sulphate, and various derivatives thereof have been oxidised with periodate at pH 3.0 and 4° and at pH 7.0 and 37°. Whereas oxidation under the latter conditions destroys all of the nonsulphated uronic acids, treatment with periodate at low pH and temperature causes selective oxidation of uronic acid residues. The reactivity of uronic acid residues depends on the nature of neighbouring 2-amino-2-deoxyglucose residues. d-Glucuronic acid residues are susceptible to oxidation when flanked by N-acetylated amino sugars, but resistant when adjacent residues are either unsubstituted or N-sulphated. L-Iduronic acid residues in their natural environment (2-deoxy-2-sulphoamino-d-glucose) are resistant to oxidation, whereas removal of N-sulphate groups renders a portion of these residues periodate-sensitive. Oxidised uronic acid residues in heparin-related glycans may be cleaved by alkali, producing a series of oligosaccharide fragments. Thus, periodate oxidation-alkaline elimination provides an additional method for the controlled degradation of heparin. 相似文献
87.
88.
Karl E. O. Åkerman 《Journal of bioenergetics and biomembranes》1977,9(1):65-72
Plots relating the initial rate of mitochondrial Ca2+ transport to the Ca2+ concentration (kinetic plots) have a hyperbolic shape in a Ca2+ concentration range of 2.5–100 µM as measured in sucrose or KCl media. In the presence of Mg2+ or a polyamine spermine, which both are competitive inhibitors of Ca2+ binding to low affinity sites at the membrane surface, the shape of the plots becomes sigmoidal. At higher concentrations of these agents linear kinetic plots are obtained as measured in a sucrose medium. In a KCl medium the sigmoidality of the kinetic plots is enhanced by an increase in the Mg2+ or spermine concentration. It is suggested that Mg2+ and spermine affect the kinetics of Ca2+ transport by interfering with Ca2+ binding to low affinity sites of the membrane surface and that the binding of Ca2+ to these sites is the first step of the mitochondrial Ca2+ transport. 相似文献
89.
Sven-Åke Persson 《Life sciences》1978,23(5):523-526
We have earlier shown that d-lysergic acid diethylamide, LSD and its 2-bromo derivative, BOL like the dopamine (DA) antagonists haloperidol increased the rate of the tyrosine hydroxylation in the striatum measured as the accumulation of DOPA after decarboxylase inhibition.Now we have found that several agents structurally similar to LSD increase the tyrosine hydroxylation in the striatum. Psilocybin (50 mg/kg i.p.) and N,N-dimethyltryptamine (50 mg/kg i.p.) caused a short-lasting increase of DOPA accumulation, while mescaline (10 – 100 mg/kg i.p.) did not increase the DOPA accumulation. A marked increase of DOPA accumulation was observed after the 5-hydroxytryptamine (5-HT) antagonist cyproheptadine. The effects of LSD and structurally related drugs on the DOPA accumulation in the striatum appear to be mediated via DA antagonism at receptor level. However, these agents may control the DOPA accumulation via other receptors than DA receptors e.g. 5-HT receptors. A control of DOPA accumulation via receptors other than DA receptors appears to be predominant after treatment with N,N-dimethyltryptamine or psilocybin. 相似文献
90.
Brion D. W. Jarvis 《Current microbiology》1983,8(3):153-158
DNA homologies at 65°C in 0.14 phosphate buffer, pH 6.8, were determined between 24 strains ofRhizobium capable of nodulatingLeucaena leucocephala and fourRhizobium reference strains. Twenty-one strains (88%) were placed in one of four DNA homology groups. The mean relative homology within a group was 65%, while the mean relative homology between groups was 20%. Thermal melting points for reassociated DNA (ΔTm(e) values) were also measured. The lack of DNA homology between groups indicates that several very different populations of bacteria are capable of nodulating and fixing nitrogen with leucaena. 相似文献