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 renal filtration, absorption and final disposal of lysozyme (lysozyme--mol wt 14,000), insulin and growth hormone were studied to gain a better quantitative understanding of the fundamental variables involved in the renal handling of low molecular weight proteins. The glomerular barrier offers little hindrance to the filtration of lysozyme, the glomerular sieving coefficient being 0.8 plus or minus 0.1 (SD). The intrarenal route by which injected lysozyme accumulates in the kidney is via filtration and subsequent absorption (uptake) by renal tubular cells. Uptake or adsorption from the peritubular side is negligible compared to luminal uptake. Renal clearance and renal titration experiments in the intact dog and in the isolated perfused rat kidney showed that the lysozyme absorption process can be best characterized as high capacity, low affinity transport system which is directly or indirectly dependent on energy input. The final disposal of absorbed 125I-lysozyme, 125I-insulin and 125I-growth hormone was studied in the isolated perfused rat kidney by measuring the radioactivity by gel chromatography. The rate of release of radioactivity as well as its nature was dependent on the molecular species of the absorbed protein. The rate of release was higher for 125I-insulin and 125I-growth hormone and lower for 125I-lysozyme. Lysozyme absorbed from the luminal side was released to the perfusate both as intact protein molecules and as catabolic products, whereas absorbed 125I-insulin was almost entirely released to the perfusate as catabolic products. It is concluded that low molecular weight proteins are extensively filtered by the kidney, absorbed from the luminal side by renal tubular cells and released back to the circulation either as intact molecules or as catabolic products (amino acids and polypeptides). This process contributes in an important way to the plasma turn-over of low molecular weight proteins including peptides and proteins hormones.
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PMID:Renal handling of low molecular weight proteins. 109 Jan 51

Interactions of several proteins with glutathione-insulin transhydrogenase (GIT) have been investigated by determining their ability to inhibit degradation of 125I-labeled insulin catalyzed by GIT. The inhibition by every insulin analog (des-Asn-des-Ala-pork insulin, desoctapeptide-pork insulin, des-Ala-pork insulin, pork insulin, proinsulin, and guinea pig insulin) was competitive vs. competitive vs. insulin indicating that they function as alternate substrates. The insulin analogs with the least hormonal activity showed the highest potency as inhigitors of insulin degradation. Whereas native ribonuclease and lysozyme showed little or no inhibition, their scrambled forms (i.e. reduced and randomly reoxidized) showed competitive inhibition with a potency greater than that of insulin. These results suggest that the conformation of the substrate or inhibitor is probably the major factor in determining the specificity for (or binding to) the enzyme. Studies withother peptide hormones showed competitive inhibition with vasopressin and oxytocin and noncompetitive inhibition with glycagon. The inhibition with growth hormone could be either competitive or noncompetitive. The inhibition by glucagon and growth hormone (physiologic antagonists of insulin) could serve as a control mechanism to modulate the activity of enzyme. The following showed very little or no inhibition; the native and scrambled form of pepsinogen, trypsin inhibitor of beef pancreas and of lima bean, C-peptide of pork proinsulin, and heptapeptide (B23-B29) of insulin.
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PMID:Interaction of insulin analogs, glucagon, growth hormone, vasopressin, oxytocin, and scrambled forms of ribonuclease and lysozyme with glytathione-insulin transhydrogenase (thiol: protein-disulfide oxidoreductase): dependence upon conformation. 117 Aug 77

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

Benzil blockade of the guanidyl group of arginine was tried on sections of paraffin-embedded tissue fixed in two different fixatives, in an attempt to evaluate the relevance of this amino acid to the reaction of several proteins with their corresponding antibodies. The two fixatives were 10% formaldehyde, and Bouin's fluid without acetic acid. Both polyclonal and monoclonal antibodies against proteins or peptides (lysozyme, adrenocorticotropic hormone, growth hormone, placental lactogen, and prolactin) were used on human biopsies or material from autopsies. The blockade was effective when monoclonal antibodies were used, whereas no effect or only a small decrease of the intensity of the reaction was observed with polyclonal antibodies. The least definitive result was obtained with prolactin, where a complete blockade was never achieved with monoclonal antibodies. Calcitonin, a peptide that does not contain arginine, was used as a control not susceptible to benzil blockade; no blockade of immunostaining was observed.
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PMID:Blockade of the antigen-antibody reaction using benzil condensation with the guanidyl residue of arginine. 172 24

Vimentin is one member of the intermediate filament multigene family which exhibits both tissue- and developmental stage-specific expression. In vivo, vimentin is expressed in cells of mesenchymal origin. Previously, we identified both enhancer and promoter elements in the chicken vimentin gene which regulate gene expression in a positive manner. In this report, we have identified a 40-base-pair region at -568 base pairs between the proximal and distal enhancer elements which represses transcriptional activity. This silencer region can also repress the heterologous herpes simplex virus thymidine kinase promoter, which is comparable to the vimentin promoter. In addition, the element is able to function in a position- and orientation-independent manner, and the amount of repression is increased by multiple copies. Here we show by gel retardation assays and DNase I footprinting that this region binds a protein in nuclear extracts from HeLa cells. Southwestern (DNA-protein) blot analysis indicates this protein is approximately 95 kilodaltons in size. Moreover, protein distribution and activity mimic the expression pattern of vimentin during myogenesis, i.e., protein binding increases as vimentin gene expression decreases. The silencer region shares strong sequence similarity with 5'-flanking sequences found in both the human and hamster vimentin genes and with other characterized silencer elements, including the human immunodeficiency virus long terminal repeat, rat growth hormone, chicken lysozyme, and rat insulin genes. Thus, a negative element appears to bind a 95-kilodalton protein involved in regulating the tissue-specific expression of the chicken vimentin gene.
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PMID:A negative element involved in vimentin gene expression. 232 56

Elevated activities of beta-D-glucuronidase, myeloperoxidase, and lysozyme were found in polymorphonuclear leukocytes (PMNs) of both hypopituitary dwarfs and normal subjects after the administration of growth hormone (GH), as compared to the activities in PMNs from blood drawn immediately before the administration of GH. During in vitro incubation, GH was able to inhibit the release of lysosomal enzymes from resting PMNs. This inhibition may be one of the reasons for the elevated lysosomal enzyme activities observed in PMNs after the administration of GH. GH can also affect hexose monophosphate shunt (HMPS) activity and superoxide production by PMNs. The activity of HMPS is stimulated by GH in resting PMNs, while in PMNs incubated with zymosan the GH inhibits both HMPS and superoxide production.
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PMID:Effect of growth hormone on the activity of some lysosomal enzymes in neutrophilic polymorphonuclear leukocytes of hypopituitary dwarfs. 299 87

A first understanding of the molecular events on the DNA level, underlying transcriptional regulation by steroid hormones, has been approached in the last 3 years by means of protein/DNA interaction studies, using purified receptors. This work summarizes our knowledge of how purified glucocorticoid and progestine receptors interact with their cognate regulatory elements associated with polymerase II dependent genes like mouse mammary tumour virus, the genes encoding human metallothionein IIA, chicken lysozyme, human growth hormone and rabbit uteroglobin. The resulting data agree with those of functional test systems, that have been gene-transfer experiments using stable transformants or transient expression. A consensus sequence for the regulatory element of the glucocorticoid receptor could be deduced that, in its three-dimensional representation, gives an impression of the steric mode of interaction. The regulatory elements of the progestine receptor overlap in two analysed cases with those of the glucocorticoid receptor, but are not identical. Furthermore, also a polymerase I transcribed gene encoding ribosomal RNA in the mouse could be shown to contain a glucocorticoid regulatory element that is functional in in vitro transcription experiments. Finally, the latest strategies are the cloning of the glucocorticoid receptor gene and the analysis of receptor-mediated topological effects.
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PMID:Mechanism of gene regulation by steroid hormones. 300 74

Confluent monolayers of MDCK (Madin-Darby canine kidney) cells provide a widely used system to study the biogenesis of epithelial cell polarity. We now report that these cells are also capable of the vectorial constitutive secretion of a major endogenous product, a glycoprotein of 81 kDa, which is released into the medium from the apical surface within 30 min of its synthesis. This release represents a bona fide exocytotic secretory process and is not the result of proteolytic cleavage of a plasma membrane-associated precursor since, in cells treated with chloroquine, a protein indistinguishable from the mature secretory product accumulated intracellularly. In contrast to the vectorial secretion of the endogenous product, a variety of exogenous exocrine and endocrine proteins synthesized in MDCK cells transfected with the corresponding genes were secreted from both the apical and basolateral surfaces. These included proteins such as rat growth hormone, chicken oviduct lysozyme, bovine gastric prochymosin, and rat salivary gland alpha 2u-globulin, which in their cells of origin are secreted via a regulated pathway, as well as the liver form of the alpha 2u-globulin and the immunoglobulin kappa chain, which are normally released constitutively. These results demonstrate the existence of secretory pathways that lead to both surfaces of MDCK cells and are accessible to the foreign secretory products. They are consistent with the operation of a sorting mechanism in which the polarized secretion of the endogenous product is effected through the recognition of signals that prevent its random distribution within the fluid phase in the cellular endomembrane system.
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PMID:Secretion of endogenous and exogenous proteins from polarized MDCK cell monolayers. 308 13

The isolation of bacterially synthesized, recombinant-DNA-derived, bovine growth hormone (r-bGH) with native structure is described. The r-bGH is found in insoluble form, in a pellet fraction, after cell breakage and centrifugation. Cell envelope components (protein, lipid, endotoxin) and nucleic acids are selectively removed from the pellet fraction by an EDTA/lysozyme/deoxycholate extraction. We demonstrate that the r-bGH is largely reduced until solubilized using 6 M guanidine/HCl. Air oxidation is then carried out, in the presence of the guanidine/HCl. The oxidation results in a mixture of about one-third disulfide-linked oligomers and two-thirds oxidized monomer. The latter may include some incorrectly oxidized material, but appears to be mostly correctly oxidized. The oxidized monomer is isolated by gel filtration in the presence of guanidine/HCl. Subsequent guanidine/HCl removal leads to refolded, oxidized r-bGH. All steps in the procedure, in particular the oxidation and refolding steps, can be carried out at relatively high protein concentrations.
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PMID:Recombinant-DNA-derived bovine growth hormone from Escherichia coli. 1. Demonstration that the hormone is expressed in reduced form, and isolation of the hormone in oxidized, native form. 354 31

Plasmids have been constructed in which promoters of 70-kDa heat-shock protein genes (hsp70) of human and Drosophila origin were linked to three different eukaryotic genes encoding human growth hormone (hGH), chicken lysozyme (cL) and a human influenza haemagglutinin (HA). Following transfection into widely divergent eukaryotic cells, the hybrid genes direct the transient, heat-regulated synthesis of the three proteins. hGH and cL are secreted into the medium. A human hsp70-hGH construct was used to establish stable mouse fibroblast lines that are capable of producing and secreting hGH at high levels following heat induction: hGH is secreted at a 500-1200-fold higher rate by heat-treated than by untreated cells.
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PMID:High-level, heat-regulated synthesis of proteins in eukaryotic cells. 356 12


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