Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The localization of D-lactate dehydrogenase in membrane vesicles prepared from Escherichia coli was studied using antibody against the purified enzyme. The activity of D-lactate dehydrogenase and D-lactate-dependent oxygen uptake of membrane vesicles prepared by using a French press were completely inhibited by this antibody, suggesting that the enzyme is localized on the outside of these vesicles. This and previous results (Futai, 1974) strongly indicate the inversion of these vesicles. The D-lactate dehydrogenase and D-lactate-dependent oxygen uptake of membrane vesicles prepared by treatment with ethylenediaminetetraacetate-lysozyme were inhibited about 15% by the antibody, whereas proline transport of the vesicles was insensitive to antibody. These results suggest that most of the membrane vesicles have D-lactate dehydrogenase on the inside of the membrane and that such vesicles transport amino acids. This essentially confirms the results of Short, Kaback, and Kohn (1975). However, unlike them we observed that a small but significant portion of activity was sensitive to the antibody as shown above. This portion may represent the completely inverted vesicles in the preparation. Ferricyanide reductase activity cannot be detected in spheroplasts, but about 30 to 50% of the total was detected in membrane vesicles prepared by treatment with ethylenediaminetetraacetate. This confirms our previous findings with membrane prepared by a slightly different procedure. It is concluded that in these vesicles about half the reactive sites for ferricyanide are moved from inside to outside the membrane, whereas 85% of the D-lactate dehydrogenase remains inside the membrane.
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PMID:Localization of D-lactate dehydrogenase in membrane vesicles prepared by using a french press or ethylenediaminetetraacetate-lysozyme from Escherichia coli. 80 22

Electron transfer activity in intact trichomes of Spirulina platensis (Nordst.) Geitl. can be observed with either CO(2) or methylviologen as the Hill acceptor. Ferricyanide cannot penetrate the intact trichomes, but photoreduction of this oxidant can be observed when mediated by lipophilic oxidants such as p-phenylenediamine or 2,5-dimethyl-p-benzoquinone. The insensitivity of these reactions to dibromothymoquinone indicates that they are due largely to the activity of photosystem II. Direct photoreduction of ferricyanide can be observed in spheroplasts of Spirulina, indicating that such preparations have altered permeability properties when compared with intact trichomes. Preparation of these spheroplasts, which are osmotically fragile, requires that intact trichomes be washed with KCl and EDTA to induce lysozyme sensitivity and thereby allow digestion of the cell wall. The KCl/EDTA washing procedure used for spheroplast preparation alters the permeability of Spirulina trichomes, as evidenced by the ability of these preparations to photoreduce ferricyanide. This photoreduction reaction is insensitive to dibromothymoquinone, and is stimulated by high concentrations of divalent cations. During assays, the reaction is inhibited by the inclusion of polyethyleneglycol as an osmotic protectant. Photoreduction of methylviologen and NADP(+) is also observed in the washed trichomes, along with an endogenously catalyzed photoreduction of O(2) to H(2)O(2). Photophosphorylation cannot be observed in the washed preparations, but cyclic photophosphorylation with phenazinemethosulfate is observed after mild sonication. These results indicate that KCl/EDTA-washed trichomes of S. platensis retain the full range of energy transducing capacities associated with thylakoid membranes of the intact trichomes; the washing procedure facilitates spheroplast formation and alters, but does not abolish, permeability barriers in these preparations.
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PMID:Photosynthetic Electron Transfer in Preparations of the Cyanobacterium Spirulina platensis. 1666 37

A new electrochemical method for the quantitation of bacteria that is rapid, inexpensive, and amenable to miniaturization is reported. Cyclic voltammetry was used to quantitate M. luteus, C. sporogenes, and E. coli JM105 in exponential and stationary phases, following exposure of screen-printed carbon working electrodes (SPCEs) to lysed culture samples. Ferricyanide was used as a probe. The detection limits (3s) were calculated and the dynamic ranges for E. coli (exponential and stationary phases), M. luteus (exponential and stationary phases), and C. sporogenes (exponential phase) lysed by lysozyme were 3 x 10(4) to 5 x 10(6) colony-forming units (CFU) mL(-1), 5 x 10(6) to 2 x 10(8) CFU mL(-1) and 3 x 10(3) to 3 x 10(5) CFU mL(-1), respectively. Good overlap was obtained between the calibration curves when the electrochemical signal was plotted against the dry bacterial weight, or between the protein concentration in the bacterial lysate. In contrast, unlysed bacteria did not change the electrochemical signal of ferricyanide. The results indicate that the reduction of the electrochemical signal in the presence of the lysate is mainly due to the fouling of the electrode by proteins. Similar results were obtained with carbon-paste electrodes although detection limits were better with SPCEs. The method described herein was applied to quantitation of bacteria in a cooling tower water sample.
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PMID:Quantitation of bacteria through adsorption of intracellular biomolecules on carbon paste and screen-printed carbon electrodes and voltammetry of redox-active probes. 1820 33