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 study the interaction between carboxyl groups and amino groups in native lysozyme [EC 3.2.1.17], and to identify the positions and the pK values of the abnormal carboxyl groups, N-acetylated lysozyme was prepared. The acetylation did not affect the molecular shape of the enzyme, but changed six amino groups to a non-ionizable form, leaving one amino group free; this was determined to be Lys 33. In addition, pH titration of the acetylated lysozyme in 0.2 or 0.02 M KCl aqueous solution indicated fewer titratable groups with pK(int) of 7.8 or 10.4 compared with the native protein, though the number of titratable carboxyl groups was not affected by the acetylation. From the pH titration results and structural considerations, the unititratable carboxyl groups were suggested to be Asp 48, Asp 66, and Asp 87. On the other hand, spectrophotometric titration in 0.2 M KCl showed that all three tyrosine residues are titratable in the acetylated protein, although an abnormal tyrosine residue exists in the native state. Tyr 20 was suggested to be untitratable in the pH range of 8-12.6.
J Biochem 1975 Dec
PMID:Titration study of acetylated lysozyme. 0 21

1. In membranes prepared from dark grown cells of Rhodopseudomonas capsulata, five cytochromes of b type (E'0 at pH 7.0 +413+/-5, +270+/-5, +148+/-5, +56+/-5 and -32+/-5 mV) can be detected by redox titrations at different pH values. The midpoint potentials of only three of these cytochromes (b148, b56, and b-32) vary as a function of pH with a slope of 30 mV per pH unit. 2. In the presence of a CO/N2 mixture, the apparent E'0 of cytochrome b270 shifts markedly towards higher potentials (+355mV); a similar but less pronounced shift is apparent also for cytochrome b150. The effect of CO on the midpoint potential of cytochrome b270 is absent in the respiration deficient mutant M6 which possesses a specific lesion in the CO-sensitive segment of the branched respiratory chain present in the wild type strain. 3. Preparations of spheroplasts with lysozyme digestion lead to the release of a large amount of cytochrome c2 and of virtually all cytochrome cc'. These preparations show a respiratory chain impaired in the electron pathway sensitive to low KCN concentration, in agreement with the proposed role of cytochrome c2 in this branch; on the contrary, the activity of the CO-sensitive branch remains unaffected, indicating that neither cytochrome c2 nor the CO-binding cytochrome cc' are involved in this pathway. 4. Membranes prepared from spheroplasts still possess a CO-binding pigment characterized by maxima at 420.5, 543 and 574 nm and minima at 431, 560 nm in C0-difference spectra and with an alpha band at 562.5 nm in reduced minus oxidized difference spectra. This membrane-bound cytochrome, which is coincident with cytochrome b270, can be classified as a typical cytochrome "0" and considered the alternative CO-sensitive oxidase.
Biochim Biophys Acta 1976 Dec 06
PMID:Energy tranduction in photosynthetic bacteria. XI. Further resolution of cytochromes of b type and the nature of the co-sensitive oxidase present in the respiratory chain of Rhodopseudomonas capsulata. 1 15

The antibacterial activity of a myeloperoxidase (MPO)-glucose oxidase system was found to be greatly increased by granulocyte elastase, present in azurophil granules of human neutrophils. The MPO-H2O3-mediated killing of both Escherichia coli and Staphylococcus aureus was potentiated by granuocyte elastase at an acid pH, whereas at pH 7.4 only killing of E. coli was potentiated. The potentiating effect of elastase was not dependent on the enzymatic properties of the protein since it was not abolished by heating, which destroys the enzymatic activity. A peptide chloromethyl ketone elastase inhibitor abolished both elastolytic activity and the pctentiating effects on MPO-H2-O2-mediated bacterial killing. The antibacterial activity of chymotrypsin-like cationic protein of human neutrophils was also potentiated by elastase. Other degradative enzymes isolated from human granulocytes, e.g., collagenase and lysozyme, did not potentiate MPO-H2O2-mediated or cationic protein-dependent bacterial killing. The present study indicates that a neutrophil constitutent, elastase, which is not microbicidal by itself, can initiate sublethal changes that render some microorganisms more susceptible to the action of microbicidal agents like MPO and chymotrypsin-like cationic protein.
Infect Immun 1976 Dec
PMID:Microbicidal mechanisms of human granulocytes: synergistic effects of granulocyte elastase and myeloperoxidase or chymotrypsin-like cationic protein. 1 11

Measurement of the enzymic activity and fluorescence properties showed that the gross conformation of acetylated lysozyme [EC 3.2.1.17] is very similar to that of the native enzyme. On the other hand, protease digestion, t-butyl hypochloride modification and thermal denaturation experiments performed on native, acetylated, and guanidinated lysozymes showed that acetylation caused a small but significant shift of the N in equilibrium with D transition to the right. Thus it can be concluded that charge balance in a protein plays an important role in maintaining its conformation. The difference between equilibrium and kinetic methods of monitoring protein denaturation was also clarified.
J Biochem 1976 Dec
PMID:A study of the native-denatured (N in equilibrium with D) transition in lysozyme. III. Effect of alteration of net charge by acetylation. 1 23

Examination of 329 pneumococcal strains showed that 41.2 per cent of the cultures had lysozyme activity. The frequency of the lysozyme feature depended on the method used. The lysozyme active strains were more frequently isolated from patients than from healthy persons and characterized by antibiotic resistance. The lysozyme feature correlated with the pneumococcal virulence with respect to albino mice, capacity for capsule formaiton and resistance to phagocytosis.
Antibiotiki 1978 Dec
PMID:[Lysozyme activity of pneumococci]. 3 35

The identification and complete assignment of the C-2 and N-1 proton nuclear magnetic resonances (NMR) of the six tryptophan residues of hen lysozyme are reported. Identification of the resonances required a detailed examination of the spectra of the protein in H2O and in 2H2O, and involved the application of spin-echo and Carr-Purcell-Meiboom-Gill pulse sequences. Assignment was achieved by observing the effects on the NMR spectra of performing specific chemical modifications, of binding paramagnetic species (lanthanide ions and spin labels), of binding inhibitors and protons and of carrying out solvent exchange experiments. The problems involved in completion of assignment are fully discussed. In the course of performing experiments to make assignments, several interesting aspects of the behaviour of the tryptophan residues in the protein structure were observed and are discussed.
Eur J Biochem 1978 Dec 01
PMID:Study of the tryptophan residues of lysozyme using 1H nuclear magnetic resonance. 3 40

30 patients on long-term lithium therapy have been studied. The results are presented of the urinary concentrating ability after water deprivation and the intranasal administration of vasopressin, of the simultaneous determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), of the minimal urine pH after an oral dose of ammonium chloride, and of the urinary beta-2-microglobulin excretion. Mean urine concentration (+/- SEM) after 22 hr water deprivation (= Uosm) amounted to 854 +/- 22 mOsm/kg H2O, mean GFR was 101 +/- 4 ml/min, mean ERPF 360 +/- 18 ml/min, and mean minimal urine pH 4.95 +/- 0.06. In 8 out of 30 patients there was polyuria. In these 8 patients the values were 778 +/- 51 mOsm/kg H2O, 113 +/- 6 ml/min, 415 +/- 33 ml/min and 4.99 +/- 0.08, respectively. Serum levels of beta-2-microglobulin and lysozyme and the urinary excretion of beta-2-microglobulin were normal in all patients. No correlation was established between Uosm and the serum lithium concentration during the test (0.8 +/- 0.05 mmoles/l) nor between Uosm and the average serum lithium level during treatment (0.79 +/- 0.03). GFR was only correlated with age. It was found that administration of indomethacin during the concentration test increased Uosm in these patients. The results suggest that, given proper dosage and surveillance, long-term treatment with lithium is not likely to cause disturbances in renal function.
Clin Nephrol 1979 Dec
PMID:A renal function study in 30 patients on long-term lithium therapy. 4 7

Quantitative analyses of cell walls from Streptococcus mutans Ingbritt grown under carbohydrate limitation in the chemostat showed that growth conditions had no statistically significant effect on the composition of polysaccharide, peptidoglycan, or the proportion of polysaccharide in the cell wall. Lysis of cell wall preparations with a muramidase supported this conclusion and further indicated that there was little difference in their overall structure. In contrast, there was a consistent difference between the rates of lysis by this enzyme of organisms grown in 0.2% glucose and 0.5% glucose. Extremes of pH or dilution rate essentially did not influence the immunogenicity of type c antigen in whole organisms irrespective of whether the carbohydrate source was glucose or sucrose. However, differences were found in the immunogenicity of lipoteichoic acid under similar circumstances. The results indicated there was an inherent phenotypic stability in the cell walls of S. mutans Ingbritt despite changes in pH, generation time, and carbohydrate source, and that any changes that did occur were probably due to associated cell-surface components.
Infect Immun 1979 Dec
PMID:Phenotypic stability of the cell wall of Streptococcus mutans Ingbritt grown under various conditions. 4 87

Strains of Escherichia coli can inhibit the in vitro growth of Neisseria gonorrhoeae. One E. coli strain released a potent agar-diffusible gonococcal growth inhibitor which was extracted and assayed in an agar well assay system. The culture conditions necessary to produce the inhibitor were determined. The inhibitor was bacteriostatic, in most cases, for N. gonorrhoeae. Based on ultrafiltration and column chromatography, the inhibitor appeared to have a molecular weight in the range of 1200 to 2000. Evidence that the molecule contained charged sites was obtained by membrane binding and column chromatography. The inhibitor was stable to extremes of heat, cold and pH. It was not volatile or susceptible to proteolytic enzymes, lysozyme, lipase, DNAase, RNAase or certain chelating agents. Its activity was completely blocked by ferric ammonium citrate. This inhibitor is dissimilar to previously reported gonococcal inhibitors of bacterial origin.
J Gen Microbiol 1979 Dec
PMID:Properties of a gonococcal inhibitor produced by Escherichia coli. 4 57

The kinetics of the bactericidal activity of 80 vol% of fresh human serum against representative 'delayed serum-sensitive' (DSS) and 'promptly serum-sensitive' (PSS) strains of Serratia marcescens were further examined with regard to various chemical and absorption procedures known to affect various components of the alternative and classical pathways of human complement activation. Inulin treatment of fresh human serum failed to diminish serum bactericidal activity against DSS and PSS assay strains. Fresh human serum that had been depleted of properdin (factor P) through absorption with zymosan, was as active as control serum against DSS strains of S. marcescens; however, PSS strains were killed in a 'delayed' fashion. Human serum that had been heat-inactivated at 50 degrees C for minutes (depletion of factor B), no longer killed DSS strains, whereas PSS strains of S. marcescens and the PSS control strain Escherichia coli C were killed in a slightly delayed fashion. Hydrazine-hydrate treatment (inactivation of C3 of the complement system) and exposure of fresh human serum to dithiothreitol completely abolished serum bactericidal activity. Bentonite-absorbed fresh human serum no longer killed DSS strains of S. marcescens; some PSS strains of S. marcescens were killed in a delayed manner, whereas control strain E. coli C was as PSS as before. Addition of Seitz-filtered fresh human serum, that lacked beta-lysin and was deficient in lysozyme, to bentonite-absorbed human serum restored bactericidal activity against DSS and PSS strains of S. marcescens; addition to heat-inactivated or Seitz-filtered, heat-inactivated human serum failed to do so. Therefore, bentonite absorption removed to a heat-labile component from fresh human serum clearly different from beta-lysin and lysozyme. Furthermore, human serum beta-lysin and lysozyme were not required for serum-mediated killing of S. marcescens strains of either serum susceptibility category.
Zentralbl Bakteriol Orig A 1979 Dec
PMID:Further characterization of "promptly" and "delayed" human serum-sensitive strains of Serratia marcescens. 4 45


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