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)

Protoplasts of Streptococcus faecalis ATCC 9790 were produced with the aid of lysozyme, and the ability of these bodies to synthesize soluble, peptide cross-linked peptidoglycan (PG) fragments was examined. Lysozyme digests of PG isolated using gel filtration from the supernatant medium of protoplasts grown in the presence of [14C]acetate and L-[3H]lysine contained small amounts of PG having KD expected for peptide cross-linked dimers and trimers. Addition of benzyl penicillin (300 mug/ml) to growing protoplast cultures did not affect the net amount of PG fragments synthesized but resulted in inhibition of synthesis of dimer and trimer fractions by 27 and 59%, respectively. Failure of penicillin to completely inhibit the accumulation of the dimer fraction was attributed to the presence of atypical forms of dimer. In fact, the supernatant medium of penicillin-treated cultures did not contain detectable amounts of typical peptide cross-linked dimer. The degree of peptide cross-linkage of protoplast PG was at most only 13% of that found in walls isolated from intact streptococci. The relative amounts of monomers, dimers, and trimers synthesized during early and late stages of protoplast growth was approximately the same. Protoplasts synthesized soluble PG fragments in amounts which were of the same order of magnitude as that expected for insoluble PG produced by an equivalent amount of intact streptococci.
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PMID:Characterization of the presumed peptide cross-links in the soluble peptidoglycan fragments synthesized by protoplasts of Streptococcus faecalis. 80 18

Human supragingival dental plaque was collected from patients with various degrees of caries and periodontal disease. Plaque extracts, prepared in five different solutions (four varied from pH 1.8 to 12.7; one contained urea), were analyzed by polyacrylamide gel electrophoresis, and tested for amylase and lysozyme enzyme activity. Because no qualitative or quantitative advantages of using the extremes of pH or urea were observed, all subsequent extracts were prepared in phosphate buffered saline at pH 7.3. Concentrated extracts were fractionated by gel filtration and characterized by polyacrylamide gel electrophoresis, peptide mapping, molecular weight estimation, determination of enzymatic activities and amino acid and carbohydrate analyses. Regions of similarity among the gels were revealed by comparing the electrophoretic patterns of pooled plaque extract, normal serum and whole saliva. The elution pattern of pooled plaque extract from a standardized Sephadex G-200 column indicated the presence of both high and low molecular weight proteins that might have correlated with the components of normal serum and saliva. A predominant and dialyzable third fraction had no correlate in either serum or saliva. The small peptides in this fraction were subjected to amino acid, carbohydrate and peptide map analyses. The most abundant amino acids were alanine, glutamic acid, glycine, valine, leucine, lysine and serine. These small components contained no neutral or amino sugars. Pooled plaque extract and the small peptides exhibited similar peptide maps.
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PMID:Studies on human dental plaque. 1. Physical and chemical characteristics and enzyme activities of pooled plaque extracts. 80 55

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

Lysozyme mRNA was translated in a reticulocyte lysate with mixtures of radioactive amino acids. The in vitro product isolated by immunoprecipitation was shown by gel electrophoresis, peptide mapping, and sequence analysis to be larger than lysozyme synthesized in vivo. An NH2-terminal extension was completely sequenced by automated Edman degradation; the phenylthiohydantoins from each cycle were separated by high pressure liquid chromatography and quantitated by scintillation spectroscopy. The NH2-terminal sequence of pre-lysozyme is: (formula: see text) where lysine is the NH2 terminus of lysozyme. Sixteen of the eighteen residues in this sequence are hydrophobic and in this regard it resembles the partial sequences recently elucidated for other secretory proteins. The NH2-terminal methionine is donated by initiator Met-tRNAfMet; thus, this sequence represents the primary translation product. This 18-amino acid sequence is cleaved from lysozyme in vivo before the lysozyme molecules are completely synthesized.
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PMID:Precursor of egg white lysozyme. Amino acid sequence of an NH2-terminal extension. 89 12

A method was devised to isolate N-terminal peptide fragments from the polypeptide chains constituting thyroglobulin even in the case when the terminal amino groups are naturally blocked, for instance, acylated. Reduced and carboxymethylated hog thyroglobulin was first acetylated and digested with thermolysin. The blocked N-terminal peptide fragments were separated from the unblocked N-terminal fragments by column chromatography on Dowex 50, then on Dowex 1 after dinitrophenylation, and finally fractionated into ten fractions by paper chromatography after gel filtration on Sephadex G-10. Structural analyses by enzymic or partial acid hydrolysis of these peptide fractions failed to detect N-terminal acetyl amino acid. Instead, pyroglutamyl peptides including pyroglutamylleucine were found. By the same method, acetylated lysine and glycine were identified for chicken lysozyme and horse myoglobin, respectively. The use of thermolysin because of its unique specificity, and the possible relevance of the present result to the previous data on the N-terminal analysis of thyroglobulin are discussed.
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PMID:The presence of N-terminal pyroglutamyl residues in hog thyroglobulin. 93 62

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

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.
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PMID:New method for determination of free amino groups in intact pure proteins: relationship to available lysine. 99 78

Conformational changes induced in antibody molecules and in their Fab fragments by binding of antigen were investigated by the circular polarization of the fluorescence emitted by the tryptophan residues. This property of the fluorescence is related to the asymmetry, and thus to the conformation and environment, of the emitting chromophore. Changes in the circular polarization of the fluorescence of the antibody were observed upon binding of RNase to anti-RNase, of poly(DL-alanyl)-poly(L-lysine) to antipoly(D-alanine), and of the "loop" of lysozyme, a monovalent antigenic determinant, to anti"loop." The spectral changes were observed at different antigen-antibody ratios, including high antigen excess, indicating that they are due to antigen binding and not to aggregation. The circular polarization of fluorescence also detects changes in conformation of the different Fab fragments upon binding of the corresponding antigens. These changes in conformation were, however, markedly different from those observed for the whole antibody molecules, and indicated an interaction between the Fc and Fab fragments in the antibody molecule, and probably a change in the conformation of Fc upon binding of antigen to the antibody. In contrast, the small hapten, phosphorylcholine, did not induce a change in the circular polarization of the fluorescence of its antibody or corresponding Fab fragments. Reduction of the interchain disulfide bonds of the antibodies abolished the antigen-induced spectral changes due to the presence of the Fc portion in the molecule, but not the changes observed in Fab, suggesting that the disulfide bonds at the hinge region of the antibody are required for the transmission of the conformational change from the Fab to the Fc.
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PMID:Antigen-induced conformational changes in antibodies and their Fab fragments studied by circular polarization of fluorescence. 105 92

The previously described peptide 62-68 (Cys 64-Cys 80) 74-96 (Cys 76-Cys 94) (Atassi, M.Z., Suliman, A.M. and Habeeb, A.F.S.A. (1975) Biochim. Biophys. Acta 405, 452-463), which accounted for about one-third of the total antigenic reactivity of native lysozyme, was isolated here with lysine 97 attached to it. The peptide was subjected to specific modification reactions in order to determine some of the residues which formed part of its antigenic reactive site. ORD measurements showed that the peptide was greatly unfolded in solution relative to its expected mode of folding within the intact lysozyme molecule. Modification of the two tryptophan residues in the peptide by reaction with 2,3-dioxo-5-indolinesulfonic acid provided a derivative which possessed similar conformational parameters to those of the unmodified peptide. However, the derivative retained only about half the immunochemical reactivity of the peptide. Succinylation of the amino groups afforded a derivative whose conformational parameters were identical to those of the unmodified peptide but in which half of the immunochemical reactivity was lost. Modification of the two tryptophan residues followed by succinylation of the amino groups resulted in almost complete loss of the antigenic reactivity, and the loss was not due to conformational differences. The antigenic reactivity of the peptide was also destroyed on removal of tryptophans 62 and 63, of sequence 84-93 from the loop 74-79 and of sequence 74-75 by chymotryptic digestion. From these and previous results it was concluded that the antigenic reactive site in this part of the lysozyme molecule incorporates one or both of tryptophans 62 and 63 as well as one or both lysines 96 and 97. The two disulfides 64-80 and 76-94 bring these two parts of the lysozyme molecule into a single reactive site. The intactness of the disulfides is essential for maintenance and reactivity of the site.
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PMID:Enzymic and immunochemical properties of lysozyme. XI. Conformation and immunochemistry of the two-disulfide peptide and the tryptophan and lysine residues in its antigenic reactivity. 118 Sep 68

The mode of reaction of benzylpenicillin with two proteins was studied, with particular reference to the allergenicity of penicillin. These reactions, with pig insulin, and with hen's-egg-white lysozyme, were carried out in neutral solution at 37 degrees C. High concentrations of penicillin are needed to label the proteins, owing to concurrent hydrolysis of penicillin. Evidence has been obtained that the penicillin-reactive sites on the insulin molecule are the alpha-amino group at the N-terminus of the A chain and the epsilon-amino group of the lysine residue; whereas a site of reaction with lysozyme appears to be the epsilon-amino group of lysine-116.
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PMID:The reaction of penicillin with proteins. 123 95


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