Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Synthesis of cell envelope proteins was studied in ethylenediaminetetraacetic acid-lysozyme spheroplasts of Escherichia coli ML30. The rate of incorporation of [3H]arginine into proteins in spheroplasts was about 30% of that of intact cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins synthesized in spheroplasts revealed the preferential synthesis of five polypeptides, one of which has been identified as the free form of murein lipoprotein. Lipoprotein synthesized in spheroplasts was found to be of same molecular size as that of mature lipoprotein. No prolipoprotein was observed even with a short pulse-labeling with [3H]arginine. On the other hand, significant accumulation of newly synthesized lipoprotein in the cytoplasmic membrane fraction of spheroplasts was observed. These results suggest that the processing of prolipoprotein occurs in the cytoplasmic membrane fraction of the cell envelope.
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PMID:Lipoprotein synthesis in Escherichia coli spheroplasts: accumulation of lipoprotein in cytoplasmic membrane. 37 Jan 2

A manual high-sensitivity sequencing method is described, in which 4-NN-dimethylaminoazobenzene 4'-isothiocyanate is used for the stepwise degradation of amino acid residues from the peptides. The 4-NN-dimethylaminoazobenzene 4'-thiazolinones of amino acids that were released, after conversion into their thiohydantoin derivatives, were identified by t.l.c. on polyamide sheets. This new method is simple and sensitive, and requires only 2-10nmol of peptides or proteins for extended sequence analysis. The method was tested on the sequence analysis of a hexapeptide (Leu-Trp-Met-Arg-Phe-Ala), bradykinin, glucagon and native lysozyme. Results show that the proposed procedure is a sensitive method for the sequence determination of short peptides as well as for the partial sequence determination of intact proteins.
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PMID:High-sensitivity sequence analysis of peptides and proteins by 4-NN-dimethylaminoazobenzene 4'-isothiocyanate. 40

The effect of various polycations on the immune response potentiated with poly I:C was studied. It was found that low molecular weight polycations had no potentiating effect. Polylysine was ineffective whereas protamine was superior to lysozyme, poly-arginine, poly-histidine, DEAE-Dextran and histone. A foot-and-mouth disease trivalent vaccine composed of strains A24 Cruzeiro, O1 Caseros and C2 Resende elicited no immune response in swine when adjuvanted with aluminium hydroxide but was effective when emulsified in oil. In general, the immune response was potentiated ten-fold when the emulsion contained poly I:C. The antibody production was in most cases further potentiated by a factor of ten when the nucleic acid double-strand was complexed with 1 : 10 (w/w) DEAE-Dextran. Protamine was as effective, or perhaps even more, than DEAE-Dextran to this effect. Guinea pigs vaccinated with a water-in-oil emulsion type monovalent C3 vaccine showed an increase in antibody production when the vaccine contained poly I:C or poly I:C complexed with 1 : 10 (w/w) protamine.
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PMID:Potentiation of FMD vaccines with polycationic-nucleic acid complexes. 59 39

1. Previous reports from this laboratory have shown that both Lys-33 and Lys-116 are parts of an antigenic site in native lysozyme. Similar studies of tyrosine derivatives indicated that one or both of Tyr-20 and Tyr-23 are located in or very close to an antigenic site in lysozyme. The site, which was located around the disulphide bridge 30-115, was recently shown unequivocally to include the residues Tyr-20, Arg-21, Lys-116, Asn-113, Arg-114, Phe-34 and Lys-33. This was confirmed by the ;surface-simulation' synthetic approach that we have recently developed, in which the foregoing eight surface residues were directly linked via peptide bonds, with intervening spacers where appropriate, into a single peptide. The peptide does not exist in native lysozyme, but simulates a surface region of it. 2. In the present work several surface-simulation peptides were synthesized representing various parts of the region, to determine the minimum structural feature that retains full antigenic reactivity and to investigate if the spatially constructed antigenic site has a preferred direction. 3. The peptide Lys-Asn-Arg-Gly-Phe-Lys exhibited a remarkable inhibitory activity towards the immune reaction of lysozyme and accounted entirely for the maximum expected reactivity of the site in the native protein (i.e. about one-third of the total lysozyme reactivity). An immunoadsorbent of the peptide bound about one-third of the total antibody to lysozyme. 4. The residues Tyr-20 and Arg-21 are not part of the site. The previously reported immunochemical effect observed on nitration of Tyr-20 was due to a deleterious ionic effect exerted by the modified tyrosine residue on the adjacent Lys-96, which is in an entirely different antigenic site of lysozyme. Thus the modification of Tyr-20 impairs the reactivity of an adjacent antigenic site, even though the residue itself is not part of a site. The conformational and immunochemical implications of this finding are discussed. 5. The antigenic site therefore comprises the five spatially adjacent residues Lys-116, Asn-113, Arg-114, Phe-34, Lys-33. The antigenic site exhibited a preferred direction (Lys-116 to Lys-33), since the reverse surface-simulation synthetic sequence was immunochemically inefficient. The site describes a line which circumscribes part [2.1nm in C((alpha))-C((alpha)) distance from Lys-116 to Lys-33] of the surface of the molecule.
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PMID:Enzymic and immunochemical properties of lysozyme. Accurate definition of the antigenic site around the disulphide bridge 30-115 (site 3) by 'surface-simulation' synthesis. 60 22

1. We have previously shown that an antigenic site (site 1) in native lysozyme resides around the disulphide bond 6-127 and, by classical synthesis of nine disulphide peptides, the antigenic site was accurately narrowed down to the structure Cys((6))-Arg((14))-[Cys((6))-Cys((127))] -Gly((126))-Arg((128)). Only a few residues on this disulphide peptide were proposed to be involved in the reactivity with antibody. However, this lacked direct verification and the role of Arg-128 remained uncertain. 2. In the present work, several peptides were designed and synthesized by the surface-simulation concept devised in our laboratory. These enabled the precise definition of the site as well as the investigation of its conformational and directional requirements. 3. The results showed that the antigenic site (site 1) is made up of the spatially contiguous surface residues: Arg-125, Arg-5, Glu-7, Arg-14, Lys-13. The surface-simulation synthetic peptide Arg-Gly-Gly-Arg-Gly-Glu-Gly-Gly-Arg-Lys (which does not exist in native lysozyme, but copies a surface region of it) accounted entirely for the maximum expected reactivity of the site (i.e. about one-third of the total antigenic reactivity of lysozyme). An immunoadsorbent of the peptide also removed about one-third of the total lysozyme antibodies. 4. The antigenic site exhibited restricted conformational freedom. The achievement of the full reactivity of the site by surface-simulation synthesis requires the appropriate choice of spacer separation between its reactive residues. The surface-simulation synthetic site exhibits the same mono-directional preference (Arg-125 to Lys-13) for the rabbit and goat antisera so far tested. The site describes a line which encircles a part (3.01 nm in C((alpha))-to-C((alpha)) distance from Arg-125 to Lys-13) of the surface of the molecule.
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PMID:Boundary refinement of the lysozyme antigenic site around the disulphide bond 6-127 (site 1) by 'surface-simulation' synthesis. 65 53

Conformational studies on an isolated integral membrane protein are reported. Lipoprotein of Escherichia coli outer membrane was released from murein by treatment with either lysozyme or trypsin. The isolated lysozyme-released lipoprotein (lipoprotein I) contained 2 or 3 muropeptides covalently linked at the C-terminal end, while the trypsin-released lipoprotein (lipoprotein II) was free of muropeptides and lacked the C-terminal peptide Tyr-Arg-Lys. Circular dichroism spectra of the two preparations were essentially identical, and they show an alpha-helix content of about 80%. According to calculations based on the Chou-Fasman rules for proteins of known sequence, lipoprotein is 64% alpha-helix and 15% beta-structure. Infrared spectroscopy qualitatively supports these values. The conformation was stable in the pH range of 5 - 12. Danaturation of lipoprotein by heat, 8 M urea, or sodium dodecylsulphate was a fully reversible, cooperative process. The thermal denaturation of lipoprotein occurs in two steps with transition points at 79.4 degrees C for lipoprotein I and at 85.1 degrees C for lipoprotein II. Lioprotein markedly changes conformation at dodecylsulphate concentrations where micelle formation sets in. The unusual behaviour of the lipoprotein convormation in sodium dodecylsulphate is discussed in relation to the lipoprotein conformation and aggregation within the membrane.
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PMID:Conformational studies on murein-lipoprotein from the outer membrane of Escherichia coli. 79 57

In order to identify the functional groups which really contribute to the carbon dioxide gas adsorption by proteins, epsilon-amino groups of lysine residues of egg albumin were chemically modified with trinitrobenzene sulfonic acid to various degrees. About 60% of the total amount of carbon dioxide gas absorbed by solid egg albumin diminished by complete modification. The amount of carbon dioxide gas adsorbed by lysozyme, its hydrolyzates and gelatin hydrolyzates depended upon the lysine content, arginine content and average molecular weight. The good correlation was obtained between the amount of carbon dioxide gas absorbed and the total of lysine and arginine content of them. The ability of carbon dioxide gas adsorption by alpha-amino group of amino acids and oligopeptides was found to be developed by the elongation of the peptide chain of glycine and other amino acid, by the removal of alpha-carboxyl group of histidine and tyrosine to corresponding amines and by the esterification of alpha-carboxyl group of leucine with p-nitrophenol. These results clearly indicate that CO2 binding sites in protein in the gas-solid phase system are epsilon-amino, alpha-amino and guanidinium groups.
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PMID:Identification and properties of reactive sites in protein capable of binding carbon dioxide in a gas-solid phase system. 87 81

In previous reports from this laboratory it was shown that an antigenic reactive site resides around the sequences 6-13 and 126-128 linked by the disulfide 6-127. The present work provides a strong support for the location of the reactive site by an independent approach. It also determines accurately the boundaries of the reactive site. 1. The two methionine residues in lysozyme were carboxyethylated by reaction with beta-propiolactone. The electrophoretically homogeneous derivative had no other modified amino acids and showed no conformational changes, relative to native lysozyme, as determined by ORD and CD measurements. However, it exhibited a slight increase in disulfide reducibility relative to native lysozyme and its lytic activity was about half that of native lysozyme, probably as a result of the slight conformational change. On the other hand, the antigenic reactivity of the derivative was equal to that of native lysozyme with several goat and rabbit antisera to lysozyem. It was therefore concluded that methionines 12 and 105 were not parts of antigenic reactive sites in native lysozyme. 2. Eleven peptides, corresponding to various sequences on the two sides of the disulfide 6-127 (i.e. two groups of peptides) were synthesized, purified and characterized. One group (A) of peptides comprised sequences 3-14, 5-14, 6-14, 5-13, 5-12 and an analog of sequence 5-14 in which methionine 12 is replaced by glycine. The second group (B) of peptides comprised sequences 125-129, 125-128, 126-128, 127-128, and 125-127. From groups A and B, nine disulfide-containing peptides (see Fig. 2) were synthesized, purified, characterized and their immunochemical interactions with antisera to native lysozyme studied. Towards each of the antisera studied here, Phe-3, Gly-4, Arg-5, Arg-125 and Leu-129 were not essential parts of the reactive site. On the other hand, Arg-14, Lys-13, Gly-126 and with some antisera Arg-128 were each critical for the reactivity of the site. Peptides from group A alone or group B alone did not inhibit the reaction of lysozyme with its antisera, confirming our previous findings that the integrity of the disulfide bond is essential for bringing the two distant (in sequence) parts of the site together. Finally, replacement of Met-12 by glycine did not influence the immunochemical reactivity of the site, confirming the above conclusion that neither of the two methionine residues takes part in interaction of lysozyme with its antibodies. An accurate delineation of the antigenic reactive site is, therefore derived here and its shape in the three-dimensional structure of native lysozyme is described.
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PMID:Enzymic and immunochemical properties of lysozyme. XIII. Accurate delineation of the reactive site around the disulfide 6-127 by immunochemical study of beta-propiolactone lysozyme derivative and of synthetic disulfide peptides. 94 82

Studies on the structure and substrate specificity of purified rat kidney nuclear (RKN) lysozyme are reported. The carboxyl and amino terminal residues of RKN-lysozyme were found to be leucine and alanine respectively. The amino acid composition indicated similarities and differences as compared with that of hen egg white (HEW) lysozyme. There were alterations in the nine amino acid residues, Lys, His, Arg, Asp, Glu, Pro, 1/2 Cys, Tyr and Trp. The other nine residues were present in identical proportions to those of HEW-lysozyme. The decrease in the arginine and aspartic acid residues was found to be compensated by the increase in the number of lysine, histidine and glutamic acid residues. The overall ratio of the acidic to basic amino acids has thus been conserved in the mammalian enzyme. In addition, RKN-lysozyme contained decreased numbers of Trp, Tyr and 1/2 Cys, and increased numbers of proline residues as found in HEW-lysozyme. RKN-lysozyme did not cross react with heterologous antibodies produced against HEW-lysozyme, and vice versa. RKN-lysozyme showed distinct specificity towards the lysis of M. luteus. Against this substrate, it was three times more efficient than HEW-lysozyme. It also cleaved E. coli B, but its efficiency was half as much as with M. luteus. However, it cleaved P. septica and B. subtilis at a rate similar to HEW-lysozyme under identical conditions.
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PMID:Structure-activity studies on mammalian tissue lytic enzymes: chemical characterization and substrate specificity of rat kidney nuclear lysozyme. 95 82

We have previously shown that an antigenic site in native lysozyme resides around the disulphide bridge 30-115 and incorporates Lys-33 and Lys-116 and one or both of Tyr-20 and Tyr-23. These residues fall in an imaginary line circumscribing part of the surface of the molecule and passing through the spatially adjacent residues Tyr-20, Arg-21, Tyr-23, Lys-116, Asn-113, Arg-114, Phe-34 and Lys-33. The identity of the site was confirmed by demonstrating that the synthetic peptide Tyr-Arg-Tyr-Gly-Lys-Asn-Arg-Gly-Phe-Lys (which does not exist in lysozyme but simulates a surface region of it), and an analogue in which glycine replaced Tyr-23, possessed remarkable immuno-chemical reactivity that accounted entirely for the expected reactivity of the site in native lysozyme. Tyr-23 is not part of the site, and its contribution was satisfied by a glycine spacer. The novel approach presents a powerful technique for the delineation of antigenic (and other binding) sites in native proteins and confirms that these need not always comprise residues in direct peptide linkage.
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PMID:Delineation of the third antigenic site of lysozyme by application of a novel 'surface-simulation' synthetic approach directly linking the conformationally adjacent residues forming the site. 99 47


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