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)

Hevamine, an enzyme with both lysozyme and chitinase activity, was isolated and purified from Hevea brasiliensis (rubber tree) latex. The enzyme (molecular weight 29,000) is homologous to certain "pathogenesis-related" proteins from plants, but not to hen egg-white or phage T4 lysozyme. To investigate the atomic details of the substrate specificity and the cause for hevamine's low pH optimum (pH 4.0), we have crystallized two hevamine isozymes as a first step towards a high-resolution X-ray structure determination. Suitable crystals were obtained at room temperature from hanging drop experiments by vapor diffusion against 1.7 M to 3.4 M-NaCl (pH 5.0 to 9.0) for the major isozyme, and by vapor diffusion against 2.5 M to 4.3 M-NaCl (pH 5.0 to 8.0) for the minor one. Both isozymes give the same crystal morphology and space group. Their space group is P2(1)2(1)2(1) with cell dimensions a = 82.3 A, b = 58.1 A and c = 52.5 A (1 A = 0.1 nm). The crystals diffract to at least 2.0 A resolution.
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PMID:Crystallization of hevamine, an enzyme with lysozyme/chitinase activity from Hevea brasiliensis latex. 232 27

The circular dichroism (CD) active phospholipid bis(4'-n-octanoxyazobenzene-4-carboxyl)-L-alpha-phosphatidylcholin e (CDPC) was used to study the effects of carboxymethyl-chitin (CM-chitin) on the membrane dynamics. For this purpose, CD and electronic spectra were observed for a mixture of CM-chitin and liposomes composed of CDPC and egg lecithin (EPC) (50% CDPC-EPC-liposomes), and for a mixture of CM-chitin, 50% CDPC-EPC-liposomes, and EPC-liposomes. CM-chitin at concentrations higher than ca. 10(-5) M induced the increase of absorbance at 600 nm synchronized with the dilution of CDPC in 50% CDPC-EPC-liposomes by EPC matrix, indicating that CM-chitin induces the fusion among a few liposomes and/or the lipid transfer through the transient liposome fusion. Temperature dependent CD spectra of a mixture of the 50% CDCP-EPC-liposomes and CM-chitin suggested that even high concentration of CM-chitin has no significant perturbation of the lipid organization in the membranes. The effects of CM-chitin on the leakage of [3H]sucrose from the EPC-liposomes were also studied. By the presence of 5 X 10(-6) M CM-chitin, the half-life for leakage of [3H]sucrose in plasma was increased by 4 times. This effect of CM-chitin was reduced by chitinase, while no effect was observed with lysozyme, suggesting that CM-chitin molecules are adsorbed on the liposome surface and stabilize the liposomes against the plasma proteins.
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PMID:Circular dichroism study of membrane dynamics. Effects of carboxymethyl-chitin. 236 52

Partially N-acetylated derivatives (degree of substitution (d.s.) 0.2, 0.4, 0.6 and 0.8 for N-acetyl) of chitosan were prepared from prawn shell chitosan, and their susceptibility towards a lysozyme from hen egg-white, three microbial chitinases and a chitinase from potato skins was examined. The partially N-acetylated derivatives (d.s. 0.4-0.8 for N-acetyl) were 1.5-4.0 times more digestible than N-acetylchitosan (d.s. 1.0 for N-acetyl), and their enzymic hydrolysis rate is controlled by the d.s. for N-acetyl group. These data suggest that chitosan is usable as a digestible material in the biomedical and biotechnological fields.
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PMID:N-acetylation in chitosan and the rate of its enzymic hydrolysis. 260 89

An extracellular, acidic chitinase was purified to homogeneity from tobacco necrosis virus-infected leaves of Cucumis sativis. The amino acid sequences of the intact protein and of peptides isolated following endoproteinase Lys-C digestion, cyanogen bromide cleavage, and trypsin digestion were determined. Oligonucleotide probes derived from this sequence were used to isolate a cDNA clone encoding this protein. No significant homology was found between this chitinase and either the basic chitinase isolated from bean or tobacco or the chitinase isolated from Serratia marcescens; however, strong homology was found between the cucumber chitinase and a lysozyme/chitinase from Parthenocissus quinquifolia. The induction of the protein by tobacco necrosis virus infection or salicylate was found to be at the level of RNA accumulation. Genomic Southern analysis indicates that a single gene in the cucumber genome encodes this protein.
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PMID:Isolation of a complementary DNA encoding a chitinase with structural homology to a bifunctional lysozyme/chitinase. 291 85

Liposome-type artificial red blood cells (ARBC) stabilized with carboxymethyl chitin (CM chitin) containing human hemolysate were prepared by a two-step emulsification technique, Oxygen binding abilities of the ARBC and human hemolysate were measured by the use of a Clark-type oxygen electrode. Both of theARBC and human hemolysate exhibited a striking similarity in oxygenation behavior, indicating that the oxygen binding ability of the former is almost identical with that of the latter. Disintegration tests on the ARBC using the enzymes (lysozyme, chitinase and phospholipase C), that can digest the components of the ARBC membrane, suggested that the membrane has a structure in which the phospholipid layer is covered by a mesh of CM chitin molecules. The acute toxicity of the ARBC to male mice (BALB/c) was examined and the LD 50 value of the ARBC for 2 ml of intravenous injection was evaluated to be 13.8 ml/kg by means of the Litchfield-Wilcoxon method.
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PMID:Liposome-type artificial red blood cells stabilized with carboxymethyl chitin. 408 52

Spherules of Coccidioides immitis strain Silveira produced in vitro were treated with chitinase and lysozyme. The walls of merthiolate-killed mature endosporulating spherules were degraded by chitinase (500 mug/ml) and by lysozyme (100 and 500 mug/ml). Thus, as was visible through the light microscope, the spherule wall was reduced in thickness from 1 to 2 mum to less than 0.5 mum. The degradation was evident also by release of N-acetylglucosamine, three times as much N-acetylglucosamine being released by chitinase in 12 h as was released by lysozyme in 3 days. However, the effect of lysozyme on living mature spherules was in marked contrast to the effect of chitinase in that treatment with lysozyme led to marked reduction in viability. Exposure to lysozyme (500 mug/ml) for 48 h permitted survival of only 0 to 0.2% of spherules. Thinning of the walls was observed only in the larger spherules (25-35 mum) treated with lysozyme. By contrast, chitinase (500 mug/ml) led to complete dissolution of the walls of living mature spherules but the viability of the liberated endospores was unaffected during contact with chitinase for 48 h. Living non-endosporulating immature spherules and free endospores were also rendered nonviable by lysozyme but not by chitinase.
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PMID:Effects of lysozyme and chitinase on the spherules of Coccidioides immitis in vitro. 476 5

A strong lytic activity against Micrococcus luteus was demonstrated in abomasal secretions from calf, adult cattle, goat and sheep. This bacteriolytic activity was undetectable in other secretions. Bacteriolysis was caused by a glycosidase displaying endo-N-acetylmuramoylhydrolase specificity (EC 3.2.1.17) and was further characterized in the calf. This lysozyme also displayed significant chitinase activity. Immunofluorescence microscopy confirmed the secretion of lysozyme by abomasal gastric glands exclusively. Electrofocusing revealed multiple molecular forms, the predominant one (more than 80%) being characterized by Mr approx. 15,000, pH optimum 5.0, pl 7.5 and remarkable conformational stability. The lytic activity of lysozyme was ionic strength dependent and competitive inhibition was observed with both N-acetyl glucosamine and N-acetyl-muramic acid. Amino-acid analysis demonstrated common characteristics with known lysozymes, i.e. four disulphide bridges, two proline and N-terminal lysine. Structural homology between the three ruminant lysozymes was established by immunological cross-reactivity.
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PMID:Lysozyme, an abomasal enzyme in the ruminants. 667 86

N-Formyl, N-chloroacetyl, N-glycyl, N-isobutyryl, and N-pentanoyl derivatives of chitosan have been prepared. N-Acetylchitosan was the derivative most susceptible to chitinase from Streptomyces griseus and lysozyme from chicken egg-white, but with respect to R in the RCOHN group were CH3 > CH3CH2 > H > CH3CH2CH2 > (CH3)2CH > NH2CH2 > CICH2. Neither enzyme hydrolysed chitosan or its N-methylene. N-benzylidene, N-benzoyl, N-nicotinyl, and N-fatty acyl (C5-C18) derivatives, and lysozyme did not hydrolyse N-butyrychitosan. N-Acetylhexanoyl-chitosans, which had d.s. ratios of approximately 0.7: approximately 0.3 and approximately 0.3: approximately 0.7, were hydrolysed at approximately 0.75 and approximately 0.004 of the rate of N-acetylchitosan (powder) by chitinase. O-Acylation of N-acylchitosans caused a decrease in the rates of hydrolysis by chitinase. N-Acetylchitosan gels were hydrolysed at 8-13 times the rate for crab-shell chitin. These results indicate that not only N- and O-substituents but also the physical form of the substrates influence the rates of hydrolysis by these enzymes.
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PMID:The effects of N-substitution of chitosan and the physical form of the products on the rate of hydrolysis by chitinase from Streptomyces griseus. 677 58

A glycosidase displaying endo-N-acetylmuramoylhydrolase specificity (EC 3.2.1.17) was isolated from calf rennet. This lysozyme was also present in abomasal secretions from calf and adult cattle. Multiple molecular forms revealed by electrofocusing might be artefacts. The main enzyme form had Mr approx. 15 000, pH optimum 5.0, pI7.5, and a remarkable conformation stability. Competitive inhibition was observed with both N-acetylglucosamine and N-acetylmuramic acid, with apparent Ki values of 29 mM and 2.4 mM respectively. The isolated enzyme also displayed significant chitinase activity.
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PMID:Calf rennet lysozyme. 680 89

Optimal conditions for the formation and isolation of protoplasts from the fungus Penicillium brevi-compactum were investigated. Localization of ribonuclease, glucosoisomerase and beta-1,3-glucanase in the mycelium was examined. To produce protoplasts, the mycelium was treated for 3-4 hours at 40 degrees C with the incubation mixture, containing chitinase from Actinomyces kurssanovii, lytic enzymes from Act. cellulose, lysozyme and 0.8 M mannitol as an osmotic stabilizer. The levels of activities of RNase, beta-1,3-glucanase, and glucosoisomerase were measured in the fungal mycelium before preparation of protoplasts, in the incubation mixture after their preparation, and in the protoplast lysate. The protoplast formation facilitated the release of RNase, beta-1,3-glucanase and glucosoisomerase from the fungal mycelium into the incubation mixture.
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PMID:[Preparation of protoplasts and localization of ribonuclease, beta-1,3-glucanase and glucosoisomerase in the fungal mycelium of Penicillium brevi-compactum]. 738 13


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