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 antibody response to a defined protein antigen, hen egg white lysozyme (HEL) has been investigated using an aminopeptidase-treated HEL molecule, des-1,2,3-HEL (AP-HEL). Surprisingly, removal of these three N-terminal residues eliminates an epitope which is a dominant B cell determinant recognized in the primary antibody response to HEL. Thus, the initial antibody response focuses on a very small region of the molecule. Even more striking is the observation that removal of this epitope markedly reduces the immunogenicity of HEL. Therefore, the epitope is not only the focus of the primary antibody response, but is essential for the initiation of the response. This report demonstrates that a selective mechanism must be activated during the response to this protein antigen. Of the multitude of B cell determinants present on HEL, only a limited number are focused upon by the immune system.
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PMID:Immunodominant protein epitopes. II. The primary antibody response to hen egg white lysozyme requires and focuses upon a unique N-terminal epitope. 620 29

A correlation was found between the level of the tissue enzyme activity in cadaveric kidneys perfusates and the degree of their functional adequacy in the early posttransplantation period. According to the data obtained the level of the activity of leucin aminopeptidase and gamma-glutamyltranspeptidase in the perfusates may be of importance for prognostication of a delayed function of the kidneys after transplantation. An elevated level of activity, in addition to leucin adminopeptidase and gamma-glutamyltranspeptidase, lactatedehydrogenase, aspartataminotransferase, muramidase, acid and alkali phosphatases suggests the transplanted kidney to be not functioning.
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PMID:[Tissue enzymatic study in the perfusate of cadaveric kidneys for assessing their functional state]. 699 3

Hamster intestinal hydrolase activities were studied after pancreatic duct ligation for periods of 5, 7, 10, 15 and 30 days. From the 7th to the 10th day, maltase and sucrase were significantly increased in the jejunoileum. Higher levels were observed on day 7 in the duodenum for all the brush-border enzyme activities (maltase, sucrase, aminopeptidase, alkaline phosphatase). Intestinal lysozyme significantly increased from the 5th to the 15th day with a maximal level at the 7th day. The increased levels of brush-border enzymes observed here are not in accordance with our description of villous atrophy after pancreatic duct ligation in the hamster. On the other hand, the important increase in lysozyme activity is in good agreement with hypertrophy and hyperplasia of the Paneth cells which we observed during our morphological study. The morphological and biochemical findings on hamster small intestine confirm the effects of exocrine pancreatic secretion both on differentiation and on enzymatic levels of the mucosa. Besides, this experiment agrees with the direct desorbing action of the pancreatic juice on the brush border and suggests another hypothetical mechanism, still worth being investigated, to explain increased brush-border activities in the duodenum and increased levels of lysozyme in the jejunoileum.
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PMID:Effect of pancreatic duct ligation on the hamster intestinal mucosa. Variation of several hydrolases. 722 72

We tested the diagnostic sensitivity of various urinary analytes for detecting cadmium-induced nephropathy at an early stage. We investigated 73 healthy persons (control group 1) and individuals exposed to cadmium, either environmentally (n = 36, risk group 2) or occupationally (n = 62, exposed group 3). All data were related to limits of the central 95% reference intervals of the control group. The serum creatinine and ribonuclease values, indicators of the glomerular filtration rate, were not different in the three groups. In the exposed persons (group 3), proximal tubular indicators (low-M(r) proteins lysozyme, ribonuclease, retinol-binding protein, and alpha 1-microglobulin) were more often increased than the glomerular indices (higher-M(r) proteins transferrin, IgG, and albumin). Both the low-M(r) proteins and tubular enzymes were differently altered in their excretion rates. Alanine aminopeptidase, alkaline phosphatase, and N-acetyl-beta-D-glucosaminidase increased even in the risk group 2. alpha 1-Microglobulin was increased in the exposed persons whose cadmium excretion was < 5 mumol/mol creatinine. The combined determination of alpha 1-microglobulin and N-acetyl-beta-D-glucosaminidase exceeded the corresponding upper reference limits in 30% of group 2 and 39% of group 3. We recommend screening for these two analytes to detect cadmium-induced renal dysfunction at an early stage.
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PMID:Urinary proteins and enzymes as early indicators of renal dysfunction in chronic exposure to cadmium. 848 64

In this study, native cells of Streptococcus mutans VA-29R and Streptococcus rattus FA-1 displayed significantly higher aminopeptidase activity than did cells of Streptococcus cricetus AHT or Streptococcus sobrinus 6715 toward the nitroanilide derivatives of leucine, alanine, methionine, arginine, and lysine. These differences in cellular aminopeptidase activity led us to investigate the subcellular localization of the aminopeptidase in these mutans group streptococci. Following conversion of native cells to protoplasts by treatment with lysozyme, most of the aminopeptidase activity detected in the native-cell preparations remained associated with the intact protoplasts. After lysis of protoplasts and differential centrifugation, most of the total cellular aminopeptidase activity was recovered with the cytoplasmic fraction. Membrane-associated aminopeptidases represented only minor activities in these mutans group streptococci. Although the four strains showed no differences with respect to a predominant cytoplasmic localization for the aminopeptidase activities, the levels of activity in the cytoplasmic fractions from S. cricetus AHT and S. sobrinus 6715 were significantly lower than those measurable in the corresponding fractions from S. mutans VA-29R and S. rattus FA-1. These results support the conclusion that the differences in aminopeptidase activity expressed by these streptococci reflect quantitative differences rather than differences in enzyme subcellular localization.
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PMID:Comparison of aminopeptidase activities in four strains of mutans group oral streptococci. 841 40

By employing various synthetic substrates, as well as soluble denatured protein substrate (TAP-lysozyme) and its derivatives, endopeptidase activity of cathepsin C, dipeptidyl aminopeptidase I [EC 3.4.14.1], from bovine spleen was investigated. Cathepsin C efficiently degraded Z-Phe-Arg-MCA, Pro-Phe-Arg-MCA, and Suc-Leu-Leu-Val-Tyr-MCA. This endopeptidase activity required sulfhydryl reagents and halide ions, as in the case of the dipeptidyl aminopeptidase (DAP) activity. We confirmed that this endopeptidase activity is due to cathepsin C itself based on the results on gel-filtration and anion-exchange chromatographies, comparative studies of the inhibitory effects of leupeptin and E-64 on this activity and those of cathepsins B and L, and further the competitive inhibitions by mutual substrates for the DAP and endopeptidase activities of cathepsin C. We also found that cathepsin C endopeptidase activity towards TAP-lysozyme and its N-alpha-acetylated tryptic peptides showed marked dependence on sulfhydryl reagents and chloride ion. Thus, we concluded that cathepsin C has endopeptidase activity as well as DAP activity. The binding energy between the enzyme and the amino acid side chains of the substrate may be as important for the endopeptidase activity as is the electrostatic interaction between the enzyme and the free alpha-amino group of the substrate for the DAP activity.
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PMID:Endopeptidase activity of cathepsin C, dipeptidyl aminopeptidase I, from bovine spleen. 851 33

A 1.4-kb gene encoding the "small" sialidase isoenzyme of Clostridium perfringens A99, including its own promoter, was previously cloned in and expressed by Escherichia coli JM 101. Since all attempts to purify this enzyme to homogeneity were unsuccessful, a new strategy was developed. The structural gene was amplified by means of a PCR technique and inserted into the plasmid vector pQE-10, transferring a six-histidine affinity tag (His6) to the N-terminus of the protein. In order to minimize proteolytic degradation of the sialidase protein, the gene was subcloned into the Escherichia coli strain BL21(DE3)pLys S with reduced protease activity. The sialidase production was increased about 2.5-fold when compared with that of the original clone. The enzyme, released by lysozyme treatment of the bacterial cells, was purified by metal chelate chromatography on Ni-nitrilo-triacetic acid agarose to apparent homogeneity in SDS-PAGE. The 42-kDa protein was enriched 62-fold with a yield of 82% and a specific activity of 280 U mg-1. A total amount of 1 mg sialidase was obtained from 1 liter of bacterial culture. For future studies, including crystallization experiments, the histidine affinity tag was removed from the sialidase enzyme by aminopeptidase K. The sialidase was then separated from aminopeptidase K by ion-exchange chromatography, resulting in an overall yield of 83% and a specific activity of 305 U mg-1 using 4-methylumbelliferyl- alpha-D-N-acetylneuraminic acid under standard conditions. The two forms (with or without the histidine tag) of sialidase exhibited similar kinetic properties when compared to the wild-type enzyme.
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PMID:Expression and purification of a recombinant "small" sialidase from Clostridium perfringens A99. 877 61

The complete amino acid sequence of cassowary (Casuarius casuarius) goose type lysozyme was analyzed by direct protein sequencing of peptides obtained by cleavage with trypsin, V8 protease, chymotrypsin, lysyl endopeptidase, and cyanogen bromide. The N-terminal residue of the enzyme was deduced to be a pyroglutamate group by analysis with a LC/MS/MS system equipped with the oMALDI ionization source, and then confirmed by a glutamate aminopeptidase enzyme. The blocked N-terminal is the first reported in this enzyme group. The positions of disulfide bonds in this enzyme were chemically identified as Cys4-Cys60 and Cys18-Cys29. Cassowary lysozyme was proved to consist of 185 amino acid residues and had a molecular mass of 20408 Da calculated from the amino acid sequence. The amino acid sequence of cassowary lysozyme compared to that of reported G-type lysozymes had identities of 90%, 83%, and 81%, for ostrich, goose, and black swan lysozymes, respectively. The amino acid substitutions at PyroGlu1, Glu19, Gly40, Asp82, Thr102, Thr156, and Asn167 were newly detected in this enzyme group. The substituted amino acids that might contribute to substrate binding were found at subsite B (Asn122Ser, Phe123Met). The amino acid sequences that formed three alpha-helices and three beta-sheets were completely conserved. The disulfide bond locations and catalytic amino acid were also strictly conserved. The conservation of the three alpha-helices structures and the location of disulfide bonds were considered to be important for the formation of the hydrophobic core structure of the catalytic site and for maintaining a similar three-dimensional structure in this enzyme group.
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PMID:The primary structure of cassowary (Casuarius casuarius) goose type lysozyme. 1186 97

The current experimental, clinical, and self-administered tests for the date of ovulation, both systemic tests and those involving cervical mucus, are explained and reviewed. First, the steroid and gonadotropin interrelationships throughout the cycle are described, with graphs illustrating how these and the other parameters discussed below vary throughout the cycle. The most popular test is basal body temperaure, yet a monophasic curve is recorded in 12-20% of ovulatory cycles. Cervical mucus becomes thin, fluid, alkaline, acellular, receptive to sperm, and exhibits special crystallizing and threading qualitites at ovulation. Physical properties of mucus and the softening of the cervix have been taught to women so they can identify their own ovulation dates. Chemical modifications of cervical mucus at ovulation include decline in certain soluble proteins and the appearance of others, a decrease in lysozyme and increases in alkaline phosphatase, aminopeptidase and esterase, a diminution of sialic acid and possibly the release of glucoasamine. The only hopeful practical test is an indicator-paper test for alkaline phosphatase in saliva or cervical mucus.
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PMID:[Detection and prediction of the time of ovulation]. 1233 86

A surface-bound aminopeptidase of Lactobacillus lactis cells was solubilized with lysozyme, and the extract was subjected to streptomycin sulfate precipitation, ammonium sulfate fractionation, chromatography on Sephadex G-100 and diethylaminoethyl-Sephadex A-50, and preparative polyacrylamide gel electrophoresis. The purified enzyme was homogeneous in disc electrophoretic analysis and consisted of a single polypeptide chain with a molecular weight of 78,000 to 81,000. The optimal pH and optimal temperature for enzyme activity were 6.2 to 7.2 and 47.5 degrees C, respectively, for l-lysine-4-nitroanilide as the substrate. The enzyme was activated by Co and Zn ions and inhibited by Cu, Hg, and Fe ions and by the metal-complexing reagents ethylenediaminetetraacetic acid, 1,10-phenanthroline, and alpha,alpha'-dipyridyl. Higher concentrations of substrate and hydrolysis products also inhibited the activity of the enzyme. The aminopeptidase had broad substrate specificity and hydrolyzed many amino acid arylamides and many peptides with unsubstituted NH(2)-terminal amino acids.
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PMID:Purification and Partial Characterization of an Aminopeptidase from Lactobacillus lactis. 1634 55


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