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)

The "vapor-phase" hydrazinolysis method was devised for the microdetermination of the carboxyl-terminal residue of a protein. With this method, a polypeptide sample is degraded with vaporized hydrazine. The optimum conditions for hen egg-white lysozyme were established to be 2 to 4 h at 90 or 100 degrees C, the recovery of the carboxyl-terminal leucine being about 70%. With this vapor-phase method, side reactions are reduced and the time of hydrazinolysis is shortened. The limit of quantitation for the carboxyl-terminus of a protein is about 50 pmol, as judged so far with hen egg-white lysozyme. The carboxyl-termini of several proteins were determined using this novel procedure.
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PMID:Vapor-phase hydrazinolysis for microdetermination of carboxyl-terminal amino acids of proteins. 260 8

We report the first case of angiotropic large-cell lymphoma (intravascular malignant lymphomatosis) presenting as minimal change disease (MCD) and diagnosed by renal biopsy. Neoplastic lymphoid cells were disseminated throughout the glomerular capillary bed and were associated with diffuse foot process effacement. The tumor had the immunophenotype of a B cell lymphoma (reactive with LCA and L-26 and unreactive with FVIII-R-Ag, Leu-M-1, alpha-1-antichymotrypsin, lysozyme, UCHL-1, Leu-22, kappa, and lambda). The temporal association between the onset of lymphoma and MCD, and the failure of the nephrotic syndrome to respond to immunosuppressive therapy support a role for lymphoma in the pathogenesis of MCD in this patient.
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PMID:Angiotropic large cell lymphoma (intravascular malignant lymphomatosis) of the kidney: presentation as minimal change disease. 265 92

To elucidate the role of the proline residue in the engineered signal sequence that directs the secretion of human lysozyme in Saccharomyces cerevisiae, we have remodeled an idealized signal sequence L8 = Met-Arg-(Leu)8-Pro-Leu-Ala-Ala-Leu-Gly [Yamamoto, Y., Taniyama, Y., Kikuchi, M., & Ikehara, M. (1987) Biochem. Biophys. Res. Commun. 149, 431-436] in the vicinity of the proline residue. By analyzing the secretory capability of 10 engineered signal sequences, we have shown the following. (1) The proline residue is important for the secretion of human lysozyme and is allowed at position -4, -5, or -6. (2) The secretory capability of the engineered signal sequences is correlated with their predicted conformations. (3) The functional signal sequences that we have investigated can be generalized as follows: Met-Arg-(Leu)n-Pro-(Xaa)-Ala-Leu-Gly where n equals 6-12 and Xaa is Leu, Ala, or Leu-Ala or can be omitted.
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PMID:Important role of the proline residue in the signal sequence that directs the secretion of human lysozyme in Saccharomyces cerevisiae. 265 80

Specific activity was compared between wild-type (WT) neutral protease from Bacillus stearothermophilus and mutant protease (M1; Gly144 replaced by Ala144) with enhanced thermostability. When casein was used as a substrate, M1 showed 1.5-times higher specific activity than that of WT. In contrast, the specific activities of M1 for soluble reduced lysozyme and insulin B chain were lower than those of WT by 17.2 and 13.2%, respectively. After digestion of the insulin A chain by these enzymes, the peptide products were purified and the N-terminal amino acid sequences were determined. WT enzyme cleaved insulin A chain at three sites, whereas no digestion was observed with M1. Using Z-Gly-Leu-NH2 as a substrate, the kinetic parameters were determined. The Km values are nearly equal for both enzymes, whereas the kcat of M1 (240 min-1) was much smaller compared to the WT (830 min-1). The data indicate that the mutation (addition of a methyl group) exerts an effect by changing both the catalytic velocity and thermostability.
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PMID:Addition of a methyl group changes both the catalytic velocity and thermostability of the neutral protease from Bacillus stearothermophilus. 267 40

Multiple replacements at amino acid position 3 of bacteriophage T4 lysozyme have shown that the conformational stability of the protein is directly governed by the hydrophobicity of the residue substituted (Matsumura, M., Becktel, W. J., and Matthews, B. W. (1988) Nature 334, 406-410). Of the 13 mutant lysozymes made by site-directed mutagenesis, two variants, one with valine (I3V) and the other with tyrosine (I3Y), were crystallized and their structures solved. In this report we describe the crystal structures of these variants at 1.7 A resolution. While the structure of the I3V mutant is essentially the same as that of wild-type lysozyme, the I3Y mutant has substantial changes in its structure. The most significant of these are that the side chain of the tyrosine is not accommodated within the interior of the protein and the amino-terminal polypeptide (residues 1-9) moves 0.6-1.1 A relative to the wild-type structure. Using coordinates based on the wild-type and available mutant structures, solvent accessible surface area of residue 3 as well as the adjacent 9 residues in the folded form were calculated. The free energy of stabilization based on the transfer of these residues from a fully extended form to the interior to the folded protein was found to correlate well with the protein stability determined by thermodynamic analysis. The enhanced thermostability of the variant Ile-3----Leu, relative to wild-type lysozyme, can also be rationalized by surface-area calculations based on a model-built structure. Noncrystallization of most lysozyme variants at position 3 appears to be due to disruption of intermolecular contacts in the crystal. The Ile-3----Val variant is closely isomorphous with wild-type and maintains the same crystal contacts. In the Ile-3----Tyr variant, however, a new set of contacts is made in which direct protein-protein hydrogen bonds are replaced by protein-water-protein hydrogen bonds as well as a novel hydrogen bond involving the phenolic hydroxyl of the substituted tyrosine.
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PMID:Structural studies of mutants of T4 lysozyme that alter hydrophobic stabilization. 267 24

To probe the nature of the hydrophobic cores of proteins and to test potential ways of increasing protein thermostability, an attempt was made to improve the packing within T4 bacteriophage lysozyme by engineered amino acid replacements. Two mutations, Leu-133----Phe and Ala-129----Val, which were designed to fill the largest cavities that exist in the folded structure of the native protein, were constructed. The mutant proteins have normal activities and their thermal stabilities are marginally lower than that of wild-type lysozyme. Crystal structure analysis of the mutant proteins shows that the introduced amino acids are accommodated with very little perturbation of the three-dimensional structure. Incorporation of the more bulky hydrophobic residues within the core of the protein is expected to provide an increase in hydrophobic stabilization, but this is seen to be offset by the introduction of strain. Inspection of the mutant structures shows that in each case the introduced amino acid side chain is forced to adopt a non-optimal dihedral angle X1. Strain is also observed in the form of bond angle distortion and in unfavorable van der Waals contacts. The results illustrate how the observed core structures of proteins represent a compromise between the hydrophobic effect, which will tend to maximize the core packing density, and the strain energy that would be incurred in eliminating all packing defects. The results also suggest that mutations designed to increase protein stability by filling existing cavities may be effective in some cases but are unlikely to provide a general method for increasing protein stability.
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PMID:Hydrophobic packing in T4 lysozyme probed by cavity-filling mutants. 268 39

A novel bacterial protease specifically hydrolyzing actin with the formation of a stable fragment with Mr of 36 kDa was obtained. This protease was shown to be synthesized at the stationary phase of bacterial culture growth. The actin hydrolysis by bacterial protease was inhibited by o-phenanthroline, EDTA and p-chloromercuribenzoate but not by N-ethyl-maleimide, phenylmethylsulfonylfluoride, Leu-peptin, pepstatin and other serine proteinase inhibitors. The protease was stable within the pH range of 4.5-8.5 and had an activity optimum at pH 7.0-8.0. The protease activity was maintained for 40 min at 45 degrees C and for 30 min at 50 degrees C; at 65 degrees C the enzyme was fully inactivated by 5 min heating. The protease preparations causing quantitative conversion of actin into a 36 kDa fragment did not hydrolyze casein, albumin, ovalbumin, lysozyme, DNAase I, RNAase, myosin, alpha-actinin, tropomyosin and troponin. It was assumed that the protease under consideration is a neutral metalloprotease specifically hydrolyzing actin.
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PMID:[Protease from a strain of bacteria E. coli A2, specifically cleaving actin]. 268 80

A case of localized histiocytosis X of the eyelid was reported. The patient was a 33 year-old man who had a tumorous lesion of the right lower eyelid that had not responded to antibiotic treatment. The lesion, accompanied with induration, slightly protruded on the conjunctival side, and the surface of the lesion was smooth and not ulcerative. No abnormal findings were noted by systemic and laboratory examination results. The patient underwent excision of the lesion and its surrounding tissue in the right lid. The specimen was fixed in formalin and embedded in paraffin. Histopathologic examination revealed diffuse infiltrates of many atypical histiocytes, which were immunohistochemically stained with antibodies to S-100 protein, lysozyme and Leu-M1. The diagnosis of localized histiocytosis X of the lid was made. It is possible that these atypical histiocytes may be classified as a category of T-zone histiocyte immunohistochemically. The postoperative course was uneventful and without recurrence.
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PMID:[A case of localized histiocytosis X of the eyelid]. 278 88

A variety of recently synthesized analogues of the chemotactic agent f-Met-Leu-Phe-OR modified in the backbone were tested for their ability to induce the release of lysozyme from human neutrophils. In sharp contrast to the effects of thiopeptide linkages on the biological activity of Leu5-enkephalin as previously reported, the presence of single thioamide bonds at either one of the endo-positions of the chemotactic peptide, abolished activity. Thioamide-derived linkages such as amidoximes and cyanamidines were generally also detrimental to activity, except in the cases of the cyanamidoformyl derivatives which showed enhanced activity and two amidoxime esters, one O-acetylated and the other O-esterified intramolecularly, which retained moderate activity. The mechanistic significance of these results is discussed in terms of conformational effects on receptor recognition.
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PMID:Some remarkable effects of thiopeptide and derived linkages on lysozyme release from neutrophils by esters of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe-OR). 280 25

The addition of low concentrations of the chemotactic factor fMet-Leu-Phe to rabbit neutrophils in the absence of cytochalasin B produces very little superoxide. This level of superoxide can be greatly increased in neutrophils pretreated for 30 min with 10 microM of the diacyl-glycerol kinase inhibitor R59022. This potentiation occurs also in the presence of cytochalasin B. In addition, while the small level of superoxide generated by fMet-Leu-Phe is not inhibited by the protein kinase C inhibitor 1-(5-isoquinoline-sulfonyl)-2-methyl piperazine (H-7), the increase by R59022 is completely abolished by this compound. In addition, this increase can be potentiated further by leupeptin. Unlike superoxide generation, the release of lysozyme or N-acetyl-beta-glucosaminidase produced by fMet-Leu-Phe is not stimulated by R59022. The results presented here suggest that stimulation of the oxidative burst requires the generation and the maintenance of a sufficient amount of diacylglycerol and/or the rearrangement of the cytoskeleton such as the inhibition of actin polymerization. Furthermore, the membrane-associated form of protein kinase C is the one responsible for the activation of the oxidative burst. The relationship between protein kinase C activation and the stimulated oxidative burst and the physiological role of chemotactic factors in the functions of the neutrophils are discussed.
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PMID:The diacylglycerol kinase inhibitor R59022 potentiates superoxide production but not secretion induced by fMet-Leu-Phe: effects of leupeptin and the protein kinase C inhibitor H-7. 282 10


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