共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Tippe 《生物化学与生物物理学报:生物膜》1981,641(2):395-400
The effects of inorganic cations, , saccharose and 2H2O on the electrophoretic mobility and ζ-potential of membrane vesicles from nerve myelin were measured and the results compared with the corresponding effects of the same reagents on the transition voltage, , of the nerve axon membrane. Different cation concentrations and 2H2O affect both potentials, the ζ-potential and , in a parallel way. Saccharose and , however, shift but leave the electrophoretic mobility of the myelin vesicles unchanged. These results suggest that shifts are not necessarily linked to changes in the membrane surface charge density but may also be caused by an interaction between the reagent and non-polar groups of the membrane interior. 相似文献
2.
Several populations of Prosopis reptans collected along the Texas Gulf coast were examined for their flavonoids and leaf morphology. Seventeen flavonoids were detected and the nine major ones were isolated and identified: apigenin 6- and , luteolin and its , quercetin and its , and myricetin, its and . The presence of a single chemical race was established, since all specimens from the Texas Gulf coast populations were uniform in their chemistry and leaf morphology, and chemically identical to the plant material from Argentina. However, the Argentina material exhibited slight morphological differences in that the leaves possessed less pubescence than the Texas Gulf coast plants. 相似文献
3.
R.F. Cleveland J.-V. Holtje A.J. Wicken A. Tomasz L. Daneo-Moore G.D. Shockman 《Biochemical and biophysical research communications》1975,67(3):1128-1135
Lipoteichoic acid (LTA) from several Gram-positive microorganisms, Forssman antigen (Fag) from R36A, and an acidic lipopolysaccharide (ALP) from were examined for effects on four wall lysis systems. The LTAs inhibited the N-acetylmuramidases of and , and the amidase of 168. Deacylated LTA failed to inhibit. LTAs failed to inhibit the amidase of pneumococcus. Fag inhibited the pneumococcal amidase, but had no effect on the other three systems. 相似文献
4.
More than thirty monohydroxy sterols were detected in the marine sponge , ranging from the ubiquitous 24-norcholesta-5, 22-dien-3β-o1 to the C30 sterol, 24-propylidenecholesterol. A new minor sterol was isolated and shown by spectral analysis and comparison with a synthetic sample to be (24R)-24,26-dimethy1cho1esta-5,26-dien-3β-o1 [26(29)-dehydroap1ysterol] (). 相似文献
5.
Membrane mutation related to the production of extracellular -amylase and protease in bacillus subtilis 总被引:13,自引:0,他引:13
Mutants which had a genetic character to increase the production of both α-amylase and protease simultaneously, were isolated from a transformable strain of Marburg by NTG treatment. This mutation seems to have occurred at a single gene of the bacterial chromosome and was not linked to 116 which was closely linked to the α-amylase gene. When this mutation and an α-amylase regulator gene (h) coexisted in one strain, their synergistic effect on extracellular α-amylase production ws observed. The introduction of this mutation resulted in a loss of competence for the transformation. The SDS disc gel electrophoretic profiles of the membrane proteins from the original strain, the mutants and transformants with this mutation showed a remarkable difference in one component. 相似文献
6.
Mark W. Bierner W.Michael Dennis B.Eugene Wofford 《Biochemical Systematics and Ecology》1977,5(1):23-28
Five populations of Helenium chihuahuensis were examined for flavonoid content, chromosome number and morphological characteristics. Thirteen flavonoid compounds were detected of which eleven were at least partially identified and were found to be flavones. The chromosome number was determined to be . Helenium arizonicum also was found to have a chromosome number of . Helenium chihuahuensis, H. arizonicum, H. mexicanum and H. laciniatum were compared by constructing Wagner Networks, both excluding and including flavonoid data, in order to clarify their phylogenetic relationships. 相似文献
7.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
8.
Ronald M. Hamelik Mead M. McCabe 《Biochemical and biophysical research communications》1982,106(3):875-880
An inhibitor of , endodextranase was detected in proteins prepared from batch cultures of , strains representing serotypes through . Affinity chromatography of strain 6715-49 proteins, which apparently were free of endodextranase activity, yielded an active endodextranase and, in a separate peak, the endodextranase inhibitor. The presence of the inhibitor in culture fluids accounts for the absence of endodextranase activity in batch-grown cultures of , known to produce this enzyme. 相似文献
9.
A number of lectins has been purified by affinity chromatography on O-glycosyl polyacrylamide gels. The lectins isolated (and the particular sugar ligands used in the affinity carriers) are as follows: Anguilla anguilla, serum (α-L-fucosyl-), Vicia cracca, seeds; Phaseolus lunatus, seeds; Glycine soja, seeds; Dolichos biflorus, seeds; Maclura pomifera, seeds; Sarothamnus scoparius, seeds; Helix pomatia, ablumin glands; Clitocybe nebularis, fruiting bodies (all ); Ricinus communis, seeds (β-lactosyl-); Onomis spinosa, root; Fomes fomentarius, fruiting bodies; Marasmius oreades, fruiting bodies (all ), Canavalia ensiformis, seeds, (i.e., concanavalin A) ().Physicochemical properties of Glycine soja, Dolichos bifloras, Phaseolus lunatus, Helix pomatia and Ricinus communis lectins correponded well to properties of the preparations studied earlier by other workers. For the other purified lectins the essential physicochemical data (sedimentation coefficient, molecular weight, subunit composition, electrophoretic patterns, amino acid composition, carbohydrate content, isoelectric point) were established and their precipitating, hemagglutinating and mitogenic activities determined. 相似文献
10.
The effect of fibrinogen and sialic acid content of erythrocytes on the aggregation of erythrocytes was quantitatively examined by using a rheoscope combined with a television image analyzer and a computer. (1) The electrophoretic mobility of erythrocytes was proportional to the sialic acid content of erythrocytes (the surface potential of erythrocytes could be expressed by the sialic acid content). (2) The aggregation of erythrocytes was accelerated by increasing fibrinogen concentration in the medium (due to the increased bridging force among erythrocytes) or by decreasing the sialic acid content (due to the reduction of the electrostatic repulsive force among erythrocytes). (3) An empirical equation expressing the velocity of aggregate formation (ν, in μm2/min) by the concentration of fibrinogen (, in g/dl) and the sialic acid content (, in μmol/ml red blood cells), log , was deduced. (4) The contribution of the bridging force of fibrinogen to the erythrocyte aggregation was much greater than that of the electrostatic repulsive force produced by sialic acid on the surface of erythrocytes. 相似文献
11.
S J van der Bent T J Schaafsma J C Goedheer 《Biochemical and biophysical research communications》1976,71(4):1147-1152
Triplet states have been detected and characterized by zero-field splitting parameters in , , , and , using fluorescence-detected magnetic resonance in zero-field at 4.2 K. Monitoring the 720 nm photosystem I emission, transitions between triplet spin levels have been assigned to antenna chlorophyll of one of both photosystems; photochemical reactions of chlorophyll are observed in the presence of an inhibitor and strong light, probably resulting in photoreduction and pheophytinization. 相似文献
12.
Enzymic degradation of capsular polysaccharide by the depolymerases from azotophage lysates of . , and from a strain of . was examined. The molecular size of the capsular polysaccharide was examined by molecular sieve chromatography both before and after exposure to the capsule depolymerase. The depolymerase appears to attack the polysaccharide substrate in a random fashion which results in polysaccharide fragments of a random size distribution. The ester linkages and hexuronic acids were proportionally the same in all fractions before degradation, but ester linkages were absent from the smaller polysaccharide molecules after enzyme action. The ester linkages were not the substrate bonds broken by the enzyme, but, in the case of some azotophage enzymes, they appeared to play a role in enzyme activity, possibly as recognition sites. 相似文献
13.
D E Sok C O Han W R Shieh B N Zhou C J Sih 《Biochemical and biophysical research communications》1982,104(4):1363-1370
Human leukocytes converted [3H]-(S)-15-HPETE into [3H]-14,15-LTA. Rat basophilic leukemia cells transformed 14,15-LTA into two bioactive C(14)-S-linked peptides, which have been characterized as 15(S)-hydroxy-14(R)-S-glutathionyl-5,8,10,12-icosatetraenoic acid and 15-(S)-hydroxy-14(R)-S-cysteinylglycyl-5,8,10,12-icosatetraenoic acid by comparison with synthetic specimens. 相似文献
14.
F.C. Pennington F.T. Haxo G. Borch S. Liaaen-Jensen 《Biochemical Systematics and Ecology》1985,13(3):215-219
The carotenoids of selected Cryptophyceae, Rhodomonas D3 and Cryptomonas ovata, have been examined by methods including HPLC, mass spectrometry 1H NMR and circular dichroism. has been assigned to monadoxanthin from 1H NMR and CD data; β,?-carotene possessed the common . The quantitative distribution pattern of carotenoids in Cryptophyceae established here and previously, totalling five species' is discussed in chemosystematic context. β,?-Carotene (3–8% of total) is the major carotene, accompanied by ?,?-carotene (0.2%), β,β-carotene (0–1%) and lycopene (0-trace). Zeaxanthin (2%) was identified in C. ovate. The diacetylenic alloxanthin is the major carotenoid (70–88%), and the monoacetylenic crocoxanthin (5–15%) and monadoxanthin (0–16%) less abundant. No epoxidic or allenic carotenoids could be detected. The biosynthetic precursor of acetylenic carotenoids in this primitive algal class is discussed. The significance of Cryptophyceae in the marine food chain is commented on, using alloxanthin as an indicator. 相似文献
15.
A method for demonstrating proestrogens has been developed. The method involves the incubation of the potential proestrogen with liver microsomes and NADPH in the presence of rat uteri, followed by examination of the effects of metabolism of the compound on the distribution of uterine estrogen receptor (R) in the cytosol (Rc) and in the nucleus (Rn). Thus, we examined whether DDT derivatives, which possess estrogenic activity , exhibit pro-estrogenic properties . Using this method, it appears that methoxychlor is a proestrogen, since the presence of microsomal enzymatic activity is required for methoxychlor to elicit translocation of uterine Rc into the nucleus, namely, the lowering of Rc and elevation of Rn. By contrast, o,p'DDT was active in translocating Rc and did not require the presence of microsomal enzymes for activity. 相似文献
16.
Fine structure of the recB and recC gene region of Escherichia coli 总被引:14,自引:0,他引:14
M Sasaki T Fujiyoshi K Shimada Y Takagi 《Biochemical and biophysical research communications》1982,109(2):414-422
17.
R A Jacobson L F Mazzuckelli 《Biochemical and biophysical research communications》1973,54(3):867-873
Two DNA-dependent RNA polymerases have been isolated from , a bacterium with a distinct morphological life cycle. The two enzymes are different with respect to chromatographic and electrophoretic behavior, divalent cation requirement, and template activity with different DNA species. One appears to be similar in its properties and structure to polymerase, the other is different, but the nature of the difference is not yet clear. The possible relationship of the two enzymes in a regulatory role in the life cycle has yet to be investigated. 相似文献
18.
We have characterized mutants of the gene retinal degeneration A (rdgA) in Drosophila using histology, optics, deep pseudopupil techniques, electrophysiology and phototactic testing. Earlier work showed that different mutant alleles differed in whether R7 and R8 (2 receptor types of 8 cells per facet in the compound eye) degenerated. We studied a weakly degenerate allele (without much degeneration), namely rdgAPC47, and a strongly mutant allele, rdgABS12. Our techniques all show that degeneration is more severe in rdgABS12, not only for but for R1-6 and ocelli as well. We confirm that degenerates more slowly than R1–6 in rdgAPC47. Mutants of a different gene, namely rdgB, have been widely used in studies of the visual system. Although retinal degeneration is severe in rdgA, the first synaptic neuropil in rdgA remains much more nearly normal than it does in rdgB. 相似文献
19.
Purification of plant calmodulin by fluphenazine-Sepharose affinity chromatography. 总被引:36,自引:0,他引:36
The calcium-dependent binding of phenothiazine drugs to calmodulin (Levin, R. M. and Weiss, B. (1977) Mol. Pharmacol. , 690–697) has been utilized to develop a rapid purification procedure for calmodulin based on fluphenazine-Sepharose affinity chromatography. Calmodulin from plant, a fungus, porcine brain and the coelenterate, , were easily purified by the calcium-dependent binding of calmodulin to fluphenazine-Sepharose. 相似文献
20.
D T Rogers D Saville H Bussey 《Biochemical and biophysical research communications》1979,90(1):187-193
The extracellular proteins and glycoproteins of a yeast mutant defective in killer toxin expression were separated by one and two dimensional polyacyylamide gel electrophoresis. Many mutant extracellular proteins and glycoproteins show both altered electrophoretic mobility and isoelectric points when compared with the parent strain. Altered proteins and glycoproteins from were identified with their parental counterparts by peptide mapping. The observed alterations co-segregated with the nuclear mutation in genetic crosses. 相似文献