Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.56 (insulin-degrading enzyme)
 737 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It was previously proposed (Varandani, P. T., Proc Natl Acad Sci 69:1681, 1972) that insulin is first degraded by rat liver homogenates in an enzyme-catalyzed reductive process by microsomal glutathione-insulin transhydrogenase before being proteolytically cleaved by the cytosolic enzyme activity designated insulin protease. This study was, however, carried out with concentrations of the hormone 10,000 times the maximal concentration seen in peripheral blood. In the present study, physiological levels of insulin (approximately 0.1 nM) and concentrations of reduced and oxidized glutathione approximating the reductive potentials of normal liver were used. Rates of degradation by separable particulate and soluble components of the homogenate were determined by following enzymatic conversion of [125I]-iodoinsulin to the trichloroacetic acid-solube form. Assessment of the mode of degradation was determined by gel filtration on Sephadex G-50 in the presence of 1 M acetic acid-6M urea. From these studies it was seen that 1) insulin is reduced at a very significant rate nonenzymatically; 2) during short periods of incubation (30 sec) where no significant hormone is reduced nonenzymatically, the rate of cleavage by the insulin protease present in the cytosol is extremely high and the microsomal GIT activity is negligible; and 3) insulin destruction noted in isolated liver cells and perfused liver is most probably due to the insulin protease activity of the cytosol.
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PMID:The importance of proteolysis as the initial step of insulin degradation in rat liver homogenates. 44 84

Monoclonal antibodies to a cytosolic insulin-degrading enzyme (IDE) were produced by fusing spleen cells from mouse immunized highly purified human erythrocyte IDE with mouse myeloma cells. Four monoclonal antibodies were identified by their ability to bind to 125I-insulin covalently linked to a cytosolic IDE from human erythrocytes. All four antibodies were found to remove more than 90% of the insulin-degrading activity from erythrocytes extracts, demonstrating that these antibodies were directed against an enzyme which accounts for most of this activity. By immunoprecipitation from metabolically labelled cells and immunoblot procedure, the enzyme from a variety of tissue was shown to be composed of a single polypeptide chain of apparent Mr = 110 kDa. One of these antibodies; 31H7 was coupled to Affi-Gel 10 and used for the purification of this enzyme. Immobilized antigen was eluted at more than 85% efficiency with buffers consisting of either pH2.3, 2.5M MgCl2 or with 6M urea. However, the antigen eluted under 6M urea retained the highest antigenecity (44%) and biological activity (8%) and the yield of the enzyme obtained from this procedure increased up to 17 fold as compared with the conventional method. NaDodSO4/polyacrylamide gel electrophoresis showed a single band of this protein with apparent Mr 110 kDa. These monoclonal antibodies and the purified enzyme will be useful tools for a better understanding of this enzyme, so may lead to the design of specific inhibitors of this enzyme that may be used to treat patients with excessive insulin degradation.
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PMID:[Production of monoclonal antibodies to an insulin degrading enzyme and affinity purification of the enzyme]. 331 32