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

To study the regulation of lipogenesis in adipose tissue by insulin and growth hormone during lactation, tissue was biopsied from primiparous bovines at 30 days antepartum and 60 days postpartum. Tissue was cultured for 24 hr or 48 hr in M199 with acetate and glucose, with a change of medium at 24 hr. The three in vitro treatments were: insulin and hydrocortisone at 10 and 50 ng/ml, respectively (IH); IH + 10 ng/ml of growth hormone (G10); and IH + 100 ng/ml of growth hormone (G100). IH allowed lipogenesis rates from 50% to 85% of those in fresh tissue. Addition of 10 ng/ml of growth hormone reduced (P less than 0.05) lipogenesis; at 100 ng/ml, the effect was only slightly greater. The hypothesis that insulin and growth hormone could be degraded by bovine adipose tissue was tested. Adipose tissue cell-free extracts degraded 125I-labeled insulin, but did not degrade labeled growth hormone. The insulin protease activity was further characterized and had a pH optimum of 7.1, a maximum hydrolysis of approximately 70%, and a hydrated molecular mass of approximately 23,000 daltons. Insulin proteolysis was inhibited by specific insulin protease inhibitors and stimulated by disulfide reducing agents. Bovine growth hormone, prolactin, and histone inhibited (P less than 0.05) the proteolysis of insulin, while bovine serum albumin, egg albumin, trypsin inhibitor, and lysozyme did not. Adipose tissue from pregnant and lactating bovines was sensitive to insulin and growth hormone, and growth hormone may modulate activity of an insulin-specific protease.
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PMID:Growth hormone alters metabolic effects and proteolysis of insulin in adipose tissue during lactation. 157 Mar 58

The purification of an enzyme is described, a protease, from human erythrocytes which degrades insulin with a high specificity at physiological hormone concentrations. Since the enzyme contains free sulfhydryl groups, affinity chromatography on organomercuri-Sepharose proved to be applicable as a valuable step in the isolation procedure. The purification factor amounted to approx. 6000, the yield to 8%. 1mg of purified enzyme was capable of degrading 50 pmol of insulin/min into trichloroacetic acid-soluble split products. The purified insulin-degrading enzyme was shown to be homogeneous, as demonstrated by gel chromatography, gel electrophoresis and isoelectric focusing. The isoelectric points was at pH 5.8. The molecular weight of nativ enzyme was estimated by gel chromatography and gel electrophoresis and found to be about 150 000-160 000, consisting of 4 subunits. Degradation products of insulin eluted from a Biogel P 30 column are smaller than the A-chain of the hormone, suggesting the activity of a protease. The enzyme appears to be specific for insulin in that it does not degrade other peptide hormones such as growth hormone, prolactin, or thyroid-stimulating hormone. Furthermore, the enzyme does not inactivate enzymes such as lactate dehydrogenase, aldolase, fructose 1,6-bisphosphatase, hexosephosphate isomerase or hexokinase.
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PMID:Purification to homogeneity of an insulin-degrading enzyme from human erythrocytes. 699 71