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Membrane-bound Enzyme (membrane-bound + enzyme)
Selected AbstractsExogenous and endogenous protease inhibitors in the gut of the fall armyworm larvae, Spodoptera frugiperdaARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2010Digali Lwalaba Abstract A dose-dependent inhibition of endogenous trypsin and aminopeptidase occurs in the lumen of Spodoptera frugiperda after feeding L6 larvae exogenous inhibitors soybean trypsin inhibitor (SBTI), tosyl-L-lysine chloromethyl ketone-HCl (TLCK), or bestatin, respectively, for 3 days. TLCK inhibits trypsin in tissue extracts and in secretions more strongly than SBTI. The aminopeptidase released into the lumen (containing the peritrophic membrane) is strongly inhibited by bestatin, but the membrane-bound enzyme is not. A bound enzyme may be more resistant to an inhibitor than unbound. A cross-class elevation of aminopeptidase activity occurs in response to ingested trypsin inhibitor, but there was no cross-class effect of aminopeptidase inhibitor (bestatin) on trypsin activity. An endogenous trypsin and aminopeptidase inhibitor is present in the lumen and ventricular cells. The strength of the endogenous trypsin inhibition seems to be in the same range as that resulting from ingestion of the exogenous inhibitor SBTI. In some insect species, considerable trypsin secretion occurs in unfed as well as in fed animals, and endogenous protease inhibitors might function to protect the ventricular epithelium by inactivation of trypsin when less food is available. © 2010 Wiley Periodicals, Inc. [source] Penicillin G splitting in a flow-through electro-membrane reactor with the membrane-bound enzymeASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Pavel Hasal Abstract Penicillin G (PenG) (0.05 mol dm,3 in phosphate buffer, pH = 8) was hydrolyzed in a continuous flow-through electro-membrane reactor (EMR) with the penicillin G acylase (PGA) (EC 3.5.1.11) immobilized in 10% (w/v) polyacrylamide membrane with an area of 900 mm2, thickness of 1 mm and enzyme activity of 100 U cm,3 and 160 U cm,3, respectively. The PenG was continuously fed to the substrate compartment adjacent to one membrane surface. Reaction products were washed from the membrane by a phosphate buffer solution fed to the product compartment adjacent to the other membrane surface. The mean residence time of both streams was varied from 11.3 min to 45 min. An electric field perpendicular to the membrane surface was imposed on the reactor and the electric current density was varied from 0 to 822 A m,2. Substrate conversion was determined as a function of the mean residence time, of the applied electric current density and of the enzyme activity of the membrane. The conversion increased with increasing residence time. The applied electric current increased substrate conversion by 200% at short residence times and at low enzyme activity of the membrane. Oscillatory reaction regime was evoked by step change of the mean residence time of reactant streams in the reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Localization of matrix metalloproteinase 2 within the aneurysmal and normal aortic wallBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 10 2000M. Crowther Background Current research has shed new light on the role of matrix metalloproteinase (MMP) 2 in the development of abdominal aortic aneurysms (AAAs). MMP-2 is a major protease in the wall of small aneurysms and is produced at increased levels by smooth muscle cells derived from AAAs compared with normal controls. In vivo, MMP-2 is produced as an inactive proenzyme that is activated predominantly by the cell membrane-bound enzyme, membrane type 1 matrix metalloproteinase (MT1-MMP). This study investigated the production of the MMP-2,MT1-MMP,tissue inhibitor of metalloproteinases (TIMP) 2 system within the wall of aortic aneurysms and in age-matched control arterial tissue. Methods Arterial tissue from four patients with aortic aneurysms and four age-matched aortic samples was examined for the production and expression of MMP-2, TIMP-2 and MT1-MMP protein using immunohistochemistry, in situ hybridization and in situ zymography. Results All components of the MMP-2,TIMP-2,MT1-MMP enzyme system were detected in the arterial wall of both aneurysm and control samples, specifically in the medial tissue. The enzymes co-localized with medial smooth muscle cells. Gelatinolytic activity was localized to elastin fibres in normal and aneurysmal aorta. Conclusion The presence of MT1-MMP within the media of arterial tissue suggests a powerful pathway for the activation of MMP-2. The localization of the MMP-2,TIMP-2,MT1-MMP enzyme system to the medial layer of the arterial wall gives support to the concept that this system may play an aetiological role in the pathogenesis of AAAs. © 2000 British Journal of Surgery Society Ltd [source] EXTRACELLULAR ENZYMES OF THE MICROCYSTIS AERUGINOSA PCC 7813 STRAIN ARE INHIBITED IN THE PRESENCE OF HYDROQUINONE AND PYROGALLOL, ALLELOCHEMICALS PRODUCED BY AQUATIC PLANTS,JOURNAL OF PHYCOLOGY, Issue 6 2009Dariusz Dziga Several cyanobacterial species have a high potential to dominate in marine environments and freshwater reservoirs, and the ecological and physiological reasons for this phenomenon are not understood comprehensively. In this study, the ability of a Microcystis aeruginosa Kütz. strain to produce free dissolved enzymes was documented. We have observed that this highly toxic strain releases alkaline phosphatase, leucine aminopeptidase, and ,-glucosidase into the ambient environment. Additionally, the inhibitory activity of selected phenols produced by aquatic plants on the activity of these enzymes was analyzed. The investigated compounds, pyrogallol and, to a lesser degree, hydroquinone, decreased the activity of extracellular enzymes produced by M. aeruginosa, with leucine aminopeptidase being the most sensitive to the inhibitors. The noncompetitive character of enzymatic inhibition suggests that the polyphenols produced by aquatic plants are able to influence the activity of different extracellular or membrane-bound enzymes. [source] | ||||||||||