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)

Granule contents from rat polymorphonuclear neutrophils were prepared by extraction with 0.2 M acetate (pH 4), dialyzed against phosphate-buffered saline (pH 7), and tested for bactericidal activity. Bactericidal assays consisted of mixing rat granule extract with 1 x 10(3) to 3 x 10(3) bacterial cells per ml at 37 degrees C for 1 h in a medium suited for bacterial growth. The granule extract demonstrated a distinctive dose-dependent bactericidal activity against outer membrane lipopolysaccharide mutants of Salmonella typhimurium LT-2, independent of added hydrogen peroxide or other active oxygen derivatives. The rough bacterial mutants showed an ordered increase in sensitivity to the rat lysosomal extracts inversely related to the length of their lipopolysaccharide carbohydrate side chains. Fractionation of the rat polymorphonuclear neutrophil granule extract with Sephadex G-100 column chromatography revealed an elution profile containing three major areas (peaks) of protein. Polyacrylamide gel electrophoresis and examination of enzymatic activity showed that these peaks contained myeloperoxidase (peak A), neutral protease (peak B), and lysozyme (peak C) activities. Also observed in peak C were cationic protein species whose cathodal electrophoretic migration was faster than that for lysozyme. Only peak C exhibited a bactericidal activity against the rough mutants of S. typhimurium LT-2 similar to that obtained for the unfractionated granule extract, with susceptibility of the bacterial mutants increasing with a progressive loss of carbohydrate residues in the lipopolysaccharide of the cell wall. The bactericidal activity of the peak C protein fraction was dose dependent. Boiling the unfractionated granule extract or peak C for 30 min had little affect on their antimicrobial activity when reacted against a deep-rough lipopolysaccharide mutant. However, trypsin pretreatment of these fractions significantly reduced their antimicrobial activity for the same mutant chemotype.
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PMID:Bactericidal activity of granule contents from rat polymorphonuclear leukocytes. 629 56

We had earlier overproduced the transcription activator protein C of bacteriophage Mu in a phage-T7 expression system. Although we achieved a high level of overproduction, the expression was not consistent. This could be due to the leaky expression of T7 RNA polymerase in the uninduced state. Introduction of pLysS, a plasmid encoding T7 lysozyme, a natural inhibitor of T7 RNA polymerase, resulted in consistent, but extremely low production of the C protein. To overcome this problem, we have devised an artificial regulatory circuit to obtain stabilised, consistent overproduction of C protein. The C-binding site was cloned downstream from the transcription start point of T7 lys. Upon induction, the C protein produced binds to its site with a very high affinity, possibly acting as a transcriptional roadblock for lys. This would overcome the inhibitory effect of T7 lysozyme on T7 RNA polymerase.
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PMID:An artificial regulatory circuit for stable expression of DNA-binding proteins in a T7 expression system. 918 43

We have developed a new strategy with a very tight control for the expression of cloned genes. The system employed here is the T7 promoter-based expression system in which transcription activator protein C of bacteriophage Mu (Mu C) has been cloned to serve as a repressor in the regulatory circuit. The system also includes pLysE, which encodes T7 lysozyme, an inhibitor of T7 RNA polymerase. This ensures tight regulation of cloned genes in the uninduced state. Upon induction, the expressed Mu C protein binds to its cognate site thereby repressing lys transcription driven by the tet promoter. In order to evaluate the tight control achieved in the system, and to check leaky expression, if any, we have cloned the gene for the SmaI restriction endonuclease without its cognate methylase. For this purpose, a dicistronic unit was constructed by cloning the smaIR gene downstream of the Mu C gene. SmaI expression was observed only in the induced cell extracts, demonstrating a tight control. The system could be used to express the genes of other cloned restriction enzymes and has the potential for general applications.
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PMID:Design of a novel regulatory circuit for expression of restriction endonucleases. 962 59

Amyloid nucleation through agitation was studied with beta2-microglobulin, which is responsible for dialysis-related amyloidosis, in the presence of salt under acid and neutral pH conditions. First, the aggregation of beta2-microglobulin in NaCl solutions was achieved by mildly agitating for 24 h at 37 degrees C protein solutions in three different states: acid-unfolded, salt-induced protofibrillar, and native. The formation of aggregates was confirmed by an increase in light scattering intensity of the solutions. Then, the aggregated samples were incubated without agitation at 37 degrees C for up to 25-45 days. The structural changes in the aggregated state during the incubation period were examined by means of fluorescence spectroscopy with thioflavin T, circular dichroism spectroscopy, and electron microscopy. The results revealed that all the samples in the different states produced a mature amyloid nucleus upon agitation, after which the fibrils elongated without any detectable lag phase during the incubation, with the acid-unfolded protein better suited to undergoing the structural rearrangements necessary to form amyloid fibrils than the more structured forms. The amount of aggregate including the amyloid nucleus produced by agitation from the native conformation at neutral pH was estimated to be about 9% of all the protein by an analysis using ultracentrifugation. Additionally, amyloid nucleation by agitation was similarly achieved for a different protein, hen egg-white lysozyme, in 0.5 M NaCl solution at neutral pH. Taken together, the agitation-treated aggregates of both proteins have a high propensity to produce an amyloid nucleus even at neutral pH, providing evidence that the aggregation pathway involves amyloid nucleation under entirely native conditions.
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PMID:Amyloid nucleation triggered by agitation of beta2-microglobulin under acidic and neutral pH conditions. 1821 Nov