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Separation and properties of human brain hexosaminidase C   总被引:11,自引:8,他引:3       下载免费PDF全文
Hexosaminidase C was separated from human brain supernatant by immunoadsorption of the A and B forms on to a column of immobilized antibody followed by preparative starch-block electrophoresis. There were some differences in the properties of hexosaminidase C preparations after each of these stages, shown by comparison of their heat-inactivation characteristics and filtration through Bio-Gel P-200. The C form prepared by both separation steps had properties which differed markedly from those of the A and B isoenzymes; its molecular weight was much larger, greater than 200000, it had optimum activity between pH6 and 7 and could not be successfully eluted from DEAE-cellulose, even with high salt concentrations, or from Sephadex G-200. These results seem to support the proposal that the C form is under a separate genetic control from the others.  相似文献   
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Acetylcholinesterase (AChE) has been detected on the plasma membrane of about 25% of the axons in the longitudinal smooth muscle tissue of guinea pig vas deferens. These axons are presumably cholinergic. No enzyme was detected in the remaining 75% of axons. These axons are presumably adrenergic. The plasma membrane of the Schwann cells associated with the cholinergic axons also stained for AChE. Some axon bundles contained only cholinergic or adrenergic axons while others contained both types of axon. When a cholinergic axon approached within 1100 A of a smooth muscle cell, there was a patch of AChE activity on the muscle membrane adjacent to the axon. It is suggested that these approaches are the points of effective transmission from cholinergic axons to smooth muscle cells. Butyrylcholinesterase activity was detected on the plasma membranes of all axons and smooth muscle cells in this tissue.  相似文献   
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The catabolism of plasma glycoproteins in normal and injured rats   总被引:2,自引:2,他引:0       下载免费PDF全文
The catabolism of (14)C-labelled plasma glycoprotein in rats was studied after injecting homologous plasma protein labelled in the N-acetylglucosamine and sialic acid moieties. In normal animals the catabolism was approximately described by a four-compartment model. The fractional rate of catabolism of the plasma-protein amino sugar was found to be 0.0305hr.(-1), corresponding to the degradation of 2.75mumoles/hr. The (14)C label was eliminated from the animals largely as carbon dioxide with a small proportion appearing in the urine. Freely circulating amino sugars or glycopeptides did not appear in the plasma as a result of the catabolic processes, and there was no evidence that the protein-bound amino sugars were reutilized in biosynthetic processes. A study of the distribution of (14)C label in the carcasses of animals 24hr. after injection provided evidence that the gastrointestinal tract accounted for 25-38% of the total catabolic pool; the lungs, kidneys, spleen and liver also appeared to contribute to catabolism. Studies were conducted with rats that had been treated with turpentine to induce an inflammatory reaction; the results could not be analysed kinetically, since the metabolism of plasma proteins in these animals did not appear to be in a steady state. The injected plasma protein disappeared from the intravascular pool more quickly than in normal animals, but there were no significant differences in the rates of excretion of the (14)C label.  相似文献   
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Investigation of an outbreak of lead-poisoning in 121 Gurkha soldiers showed that this was due to the contamination of chilli powder (cayenne pepper), a constituent of curry powder, with lead chromate. Comprehensive systems of food sampling are needed in developing communities.  相似文献   
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