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)

To examine the effect of amino acid substitutions in lysozyme on the binding of antibodies to lysozyme, we purified lysozyme from the egg whites of California quail and Gambel quail. Tryptic peptides were isolated from digests of the reduced and carboxymethylated lysozymes and subjected to quantitative analysis of their amino acid compositions. The two proteins were identical by this criterion. Each peptide from the California quail lysozyme was then sequenced by quantitative Edman degradation, and the peptides were ordered by homology with other bird lysozymes. California quail lysozyme is most similar in amino acid sequence to bobwhite quail lysozyme, from which it differs by two substitutions: arginine for lysine at position 68 and histidine for glutamine at position 121. California and bobwhite quail lysozymes were antigenically distinct from each other in quantitative microcomplement fixation tests, indicating that substitutions at one or both of these positions can alter the antigenic structure of lysozyme. Yet neither of these positions is among those claimed to account for the precise and entire antigenic structure of lysozyme [Atassi, M. Z., & Lee, C.-L. (1978) Biochem. J. 171, 429--434]. Two possible explanations for this discrepancy are discussed.
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PMID:Amino acid sequence of California quail lysozyme. Effect of evolutionary substitutions on the antigenic structure of lysozyme. 8 64

In order to probe the cause and nature of conformational changes induced by the chemical modification of amino groups in proteins, five acylated derivatives of ovalbumin namely 21% acetylated, 32% succinylated, 90% butyrated 92% succinylated, and 95% acetylated ovalbumins were prepared and their molecular and immunological properties were systematically investigated. As evidenced by the ultraviolet difference spectral, solvent perturbation, gel filtration, and viscosity data, acylation of the amino groups produced a definite conformational change in native ovalbumin whose extent was higher for higher degrees of chemical modification. The solvent pertubation data showed an exposure of 0.5 tryptophan and 3 tyrosine residues in native ovalbumin; the exposure increased to 1 tryptophan and about 5 tyrosine residues in the maximally modified proteins (i.e. 90% butyrated, 92% succinylated, and 95% acetylated ovalbumins). The Stokes radius (2.7 nm) and intrinsic viscosity (3.9 ml/g) of ovalbumin increased, respectively, to about 3.4 nm and 7.7 ml/g upon acylation of its 18 lysine residues; the intrinsic viscosity of 95% acetylated ovalbumin was 7.2 ml/g. The reduced viscosity of ovalbumin (4.2 ml/g) which remained unaltered on raising the pH to pH 11.2, increased to 7.9 ml/g on succinylation of 18 lysine residues. On raising the ionic strength from 0.15 to 1.0, the value decreased from 7.9 to 6.2 ml/g. These observations taken together with the fact that the intrinsic viscosities of 92% succinylated and 90% butyrated ovalbumins are identical, argue against the presently prevalent proposal that electrostatic effects alone are responsible for the disruption of native protein conformation during chemical modification. The immunological activity of ovalbumin towards rabbit anti-ovalbumin expectedly decreased with acylation of its amino groups but the three maximally modified ovalbumins retained 40% immunological activity. This taken along with the spectral and viscosity data showed substantial native structure (format) in the three maximally acylated derivatives. The rabbit antiserum against 95% acetylated ovalbumin did not cross-react with acetylated lysozyme and reacted poorly with the native and 92% succinylated ovalbumins suggesting that the antigenic make-up of the three maximally modified ovalbumins is different.
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PMID:Changes in conformation and immunological activity of ovalbumin during its modification with different acid anhydrides. 10 Dec 49

The chemical structure of the adjuvant active fraction of mycobacterial cell walls has been investigated. It had been shown previously that soluble peptidoglycan fragments obtained from cell walls of Mycobacteria by lysozyme digestion or by other treatments act as adjuvants for increasing both humoral and cellular immunity. We then found that even the monomer subunit of the peptidoglycan of Mycobacteria (i.e. a disaccharide-tetrapeptide) is adjuvant active; then, similar compounds from other strains of bacteria were tested; the monomeric subunits of meso-diaminopimelic acid as well as L-lysine containing peptidoglycans were found to be adjuvant active. The smallest active compound studied so far is N-acetyl-muramyl-L-alanyl-D-isoglutamine synthesized for us by SINAY et al. (1975).
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PMID:Peptidoglycan adjuvants: minimal structure required for activity. 12 66

The substrate specificity of the catalytic subunit of rabbit skeletal muscle 3': 5'-cyclic AMP-dependent protein kinase (EC 2.7.1.37; ATP: protein phosphotransferase) has been studied using the synthetic peptide Arg-Gly-Tyr-Ser-Leu-Gly corresponding to the sequence around serine 24, a phosphorylation site in reduced, carboxymethylated, maleylated (RCMM) chicken egg white lysozyme. This peptide served as a substrate for the enzyme and exhibited a 6-fold higher Vmax and a 100-fold higher Km than RCMM-lysozyme. Replacement of the arginine with glycine, histidine, or lysine resulted in a dramatic reduction in the Vmax. These results support the concept that arginine is an important residue in determining the substrate specificity of the protein kinase, predominantly influencing the Vmax of the phosphorylation reaction. Two synthetic peptides in which serine was replaced by an alanine acted as competitive inhibitors of phosphorylation of the synthetic peptide substrate and RCMM-lysozyme.
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PMID:Synthetic hexapeptide substrates and inhibitors of 3':5'-cyclic AMP-dependent protein kinase. 17 70

An ADP-ribosyltransferase was purified approximately 500-fold from the supernatant fraction of turkey erythrocytes. The enzyme hydrolyzed [carbonyl-(14)C]NAD to ADP-ribose and [carbonyl-(14)C]nicotinamide at a low rate. Nicotinamide formation from NAD was enhanced by arginine methyl ester > D-arginine approximately L-arginine > guanidine; lysine, histidine, and citrulline were ineffective. Incubation of [adenine-U-(14)C]NAD and arginine methyl ester or arginine with the purified enzyme resulted in the formation of new compounds that contained (14)C, reacted with ninhydrin, and quenched background fluorescence of thin-layer plates viewed in ultraviolet light. Their mobilities on thin-layer chromatograms were indistinguishable from those of ADP-ribosylarginine methyl ester and ADP-ribosylarginine formed during incubation of choleragen with NAD and arginine methyl ester or arginine, respectively [Moss, J. & Vaughan, M. (1977) J. Biol. Chem. 252, 2455-2457]. The purified transferase also catalyzed the incorporation of label from [adenine-(14)C]-NAD into lysozyme, histones and polyarginine. When the (14)C-labeled lysozyme was incubated with snake venom phosphodiesterase, the radioactivity was released and, on thin-layer chromatograms, exhibited a mobility indistinguishable from that of 5'-AMP, as would be expected of an ADP-ribosylated protein, but not of a poly(ADP-ribosylated) product. The purified transferase activated rat brain adenylate cyclase and, as is the case with choleragen, activation was absolutely dependent on NAD. The presence in the avian erythrocyte of a protein that, like choleragen and Escherichia coli heat-labile enterotoxin, apparently activates adenylate cyclase and possesses ADP-ribosyl transferase activity is consistent with the view that the mechanisms through which the bacterial toxins produce pathology are not entirely foreign to vertebrate cells, at least some of which may possess and employ an analogous mechanism for activation of adenylate cyclase.
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PMID:Isolation of an avian erythrocyte protein possessing ADP-ribosyltransferase activity and capable of activating adenylate cyclase. 21 2

A group of proteins and polyamino acids with positively charged domains were shown to inhibit the binding of 125I-LDL to its receptor on the surface of human fibroblasts. The list of inhibitory proteins included platelet factor 4 (which has a cluster of lysine residues at its carboxyl terminus), two lysine-rich histones, poly-L-lysines of chain length greater than 4, and protamine. These proteins were effective in the concentration range of 5--10 microgram/ml. Two other positively charged proteins, lysozyme and avidin, did not inhibit 125I-LDL binding. Kinetic studies suggested that protamine was not acting simply as a competitive inhibitor with regard to the LDL receptor. In light of previous data showing that polyanions such as heparin and polyphosphates also inhibit 125-I-LDL binding to its cell surface receptor, the current findings suggest that charge interactions are important in this binding reaction. In a related series of studies, a number of glycoproteins and their asialo derivatives as well as a number of sugar phosphates failed to inhibit 125I-LDL binding to its receptor in fibroblasts.
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PMID:Inhibition of the binding of low-density lipoprotein to its cell surface receptor in human fibroblasts by positively charged proteins. 21 39

1, 2-Cyclohexanedione reacts specifically with the guanidino group of arginine or arginine residues at pH 8 to 9 in sodium borate buffer in the temperature range of 25-40 degrees. The single product, N-7, N-8-(1,2-dihydroxycyclohex-1,2-ylene)-L-arginine (DHCH-arginine) is stable in acidic solutions and in borate buffers (pH 8 to 9). DHCH-Arginine is converted to N-7-adipyl-L-arginine by periodate oxidation. The structures of the two compounds were elucidated by chemical and physicochemical means. Arginine or arginyl residues can be regenerated quantitatively from DHCH-arginine by incubation at 37 degrees in hydroxylamine buffer at pH 7.0 FOR 7 TO 8 hours. Analysis of native egg white lysozyme and native as well as oxidized bovine pancreatic RNase, which were treated with cyclohexanedione, showed that only arginine residues were modified. The utility of the method in sequence studies was shown on oxidized bovine pancreatic ribonuclease A. Arginine modification was complete in 2 hours at 35 degrees in borate buffer at pH 9.0 with a 15-fold molar excess of the reagent. The derived peptides showed that tryptic hydrolysis was entirely limited to peptide bonds involving lysine residues, as shown both by two-dimensional peptide patterns and by isolation of the resulting peptides. The stability of DHCH-arginyl residues permits isolation of labeled peptides.
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PMID:Reversible modification of arginine residues. Application to sequence studies by restriction of tryptic hydrolysis to lysine residues. 23 32

Human polymorphonuclear neutrophil (PMN) granule extract (25 mug of protein) released 60 percent of the available 35SO4 from labeled rabbit articular cartilage in 0.5 hour at neutral pH. N-acetyl-L-alanyl-L-alanyl-L-prolyl-L-alanine choloromethyl ketone (NAcAAPACK), a specific elastase inhibitor, was only minimally effective against whole granule extract, and N-alpha-tosyl-L-lysine chloromethyl ketone, which inhibits trypsin but not elastase, was completely ineffective. Preparative disc-gel electrophoresis of PMN granule extract revealed two separate regions with independent activity against 35SO4-labeled cartilage. One region contained elastases and when tested alone, was completely inhibited by NAcAAPACK. The other contained lysozyme and two esterases active against N-acetyl-L-phenylalanine-alpha-naphthol. Purified lysozyme proved inactive, suggesting that the chymotrypsin-like esterases were responsible for proteoglycan degradation by this region of the gel.
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PMID:Identification of neutral proteases in human neutrophil granules that degrade articular cartilage proteoglycan. 23 25

Conversion of whole cells of Micrococcus lysodeikticus to protoplasts allowed the release of a soluble form of a D-alanine carboxypeptidase into the protoplasting medium. The enzyme cleaves the terminal D-alanine from the radioactively labelled UDP-N-acetylmuramyl-pentapeptide containing L-lysine as the diamino acid. However, the enzyme is only minimally active in this fraction so that it had to be enriched and partially purified before its properties could be studied. Chromatography on carboxymethyl-Sephadex removed the lysozyme used in the protoplasting of the cells. The material which was unadsorbed to the column was applied to an affinity chromatography column of Ampicillin-Sepharose. Most of the contaminating protein was washed from the column while the D-alanine carboxypeptidase adhered to the resin and could be eluted with 0.5 M Tris-HCl buffer pH 8.6. Some of the properties of the enzymic activity were studied using this preparation. The enzyme was activated by Mg2+ ions with a broad optimum from 15--35 mM. It was maximally active when NaCl at a concentrations of 0.06--0.08 M was added to the assay, and the pH curve was biphasic with an alkaline optimum. The Km for substrate was found to be 0.118 mM. Enzymic activity was completely inhibited by low concentrations of Ampicillin and penicillin G.
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PMID:D-alanine carboxypeptidase activity of Micrococcus lysodeikticus released into the protoplasting medium. 24 Jun 94

1. The reactivities of phenylglyoxal (PGO), glyoxal (GO), and/or methylglyoxal (MGO) with several proteins, including ribonuclease A [EC 3.1.4.22] and its derivatives, alpha-chymotrypsin [EC 3.4.21.1], trypsin [EC 3.4.21.4], lysozyme [EC 3.2.1.17], pepsin [EC 3.4.23.1], rennin [EC 3.4.23.4], thermolysin, and insulin and its B chain, have been examined. From analyses of the reaction products, PGO was shown to be the most specific for arginine residues. GO and MGO also reacted rapidly with arginine residues, but they also reacted with lysine residues to a significant extent. A side reaction with N-terminal alpha-amino groups was observed with each of these reagents. 2. Two arginine residues out of four in ribonuclease A, two out of three in alpha-chymotrypsin, one out of two in trypsin, one out of two in pepsin, and one out of five in rennin appeared to react with PGO fairly rapidly, indicating a difference in the relative accessibility of these residues by the reagent. Extensive modification of the arginine residues by PGO occurred with RCM-derivatives of ribonuclease A and insulin B chain. The N-terminal isoleucine residues of alpha-chymotrypsin and trypsin appeared to be unreactive with PGO because of salt bridge formation with an aspartyl residue. The activity of alpha-chymotrypsin toward N-benzoyl-L-tyrosine ethyl ester and the lytic activity of lysozyme were lost rapidly on treatment with PGO, as in the case of ribonuclease A. Pepsin and rennin were only partially inactivated by reaction with PGO.
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PMID:Further studies on the reactions of phenylglyoxal and related reagents with proteins. 32 41


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