Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 protoplasts of Actinomyces sp. 26--115 producing actinomycin C were obtained by the action of lysozyme on the mycelial paste of a 48-hour microbial culture. The protoplast capacity for synthesizing actinomycin was decreased as compared to that of the intact mycelium. The transport of L-isoleucine, a precursor of actinomycin C biosynthesis in the protoplasts also decreased but this could not be the only cause of the decrease in the actinomycin biosynthesis capacity. The biosynthesis of actinomycin C by the protoplasts of Actinomycin sp. 26--115 did not require galactose and was not inhibited by glucose and exogenic actinomycin.
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PMID:[Aspects of the biosynthesis of actinomycin C]. 8 46

Acid carboxypeptidase (EC 3.4.12.-) crystallized from culture filtrate of Penicillium janthinellum has been investigated for its use in carboxy-terminal sequence determination of Z-Gly-Pro-Leu-Gly, Z-Gly-Pro-Leu-Gly-Pro, angiotensin I, native lysozyme, native ribonuclease T1, and reduced S-carboxy-methyl-lysozyme. The examination indicated that proline and glycine were liberated from Z-Gly-Pro-Leu-Gly-Pro. At high enzyme concentration, the enzyme catalyzed complete sequential release of amino acids from the carboxy-terminal leucine to the amino-terminal aspartic acid of angiotensin I. The enzyme released the carboxy-terminal leucine from native lysozyme, however, no release of the threonine from native ribonuclease T1 was observed after a prolonged period of incubation with the enzyme. The sequence of the first nine carboxy-terminal residues of denatured lysozyme, leucine, arginine, S-carboxymethyl-cysteine, glycine, arginine, isoleucine, tryptophane, alanine, and glutamine, could be deduced unequivocally from a time release plot of an incubation mixture with the enzyme.
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PMID:Action of crystalline acid carboxypeptidase from Penicillium janthinellum. 23 51

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

A strain of Escherichia coli bearing a hybrid plasmid containing the psd gene, starved for isoleucine by the addition of valine, produces amounts of phosphatidyl-serine decarboxylase, a membrane-bound enzyme, about 40-fold higher than wild type. At least 98% of the enzyme from cells with high levels of decarboxylase is isolated in the inner, cytoplasmic membrane fraction if the cells are broken by osmotic lysis of spheroplasts following treatment with lysozyme/EDTA. In contrast, if cells containing these large amounts of enzyme are disrupted by sonication, 40 to 45% of the activity is recovered in the 100,000 times g supernatant fraction, whereas with wild type cells, only 5 to 10% is recovered in this fraction. About half of the decarboxylase in membranes saturated with the enzyme is thus only loosely bound, and readily removed by sonication, but not by osmotic lysis. This apparent saturation of the membrane with decarboxylase seems specific, since two other membrane-bound enzymes, phosphatidyl-glycerophosphate synthetase, and CDP-diglyceride synthetase, are not displaced into the supernatant fraction upon sonication. Fractionation on columns of agarose and by centrifugation through gradients of sucrose revealed that the decarboxylase in the supernatant is associated with lipid, in a complex with an apparent molecular weight of at least 5 times 10(6).
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PMID:Increased synthesis of phosphatidylserine decarboxylase in a strain of Escherichia coli bearing a hybrid plasmid. Altered association of enzyme with the membrane. 36 58

The mutant T4 phage lysozyme in which isoleucine 3 is replaced by proline (I3P) crystallizes in an orthorhombic form with two independent molecules in the asymmetric unit. Relative to wild-type lysozyme, which crystallizes in a trigonal form, the two I3P molecules undergo large hinge-bending displacements with the alignments of the amino-terminal and carboxy-terminal domains changed by 28.9 degrees and 32.9 degrees, respectively. The introduction of the mutation, together with the hinge-bending displacement, is associated with repacking of the side-chains of Phe4, Phe67 and Phe104. These aromatic residues are clustered close to the site of the mutation and are at the junction between the amino and carboxyl-terminal domains. As a result of this structural rearrangement the side-chain of Phe4 moves from a relatively solvent-exposed conformation to one that is largely buried. Mutant I3P also crystallizes in the same trigonal form as wild-type and, in this case, the observed structural changes are restricted to the immediate vicinity of the replacement. The main change is a shift of 0.3 to 0.5 A in the backbone of residues 1 to 5. The ability to crystallize I3P under similar conditions but in substantially different conformations suggests that the molecule undergoes large-scale hinge-bending displacements in solution. It is also likely that these conformational excursions are associated with repacking at the junction of the N-terminal and C-terminal domains. On the other hand, the analysis is complicated by possible effects of crystal packing. The different I3P crystal structures show substantial differences in the binding of solvent, both at the site of the Ile3-->Pro replacement and at other internal sites.
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PMID:Structure of a hinge-bending bacteriophage T4 lysozyme mutant, Ile3-->Pro. 140 94

From fluorescence measurements on mixtures of bis-ANS and equine lysozyme and from Ca(2+)-dependent hydrophobic interaction chromatography of equine lysozyme, it is demonstrated that Ca2+ binding induces a conformational change upon which hydrophobic regions in the protein become less accessible. Bis-ANS fluorescence titrations in the absence of Ca2+ and in 2 mM Ca2+ are also performed with equine alpha-lactalbumin variants B and C. These variants differ by an amino-acid exchange Asp----Ile at residue 95. The fluorescence titration curves indicate that the accessibility of the probe to the Ca2+ conformers is clearly influenced by the mutation. The Ca(2+)-dependent exclusion of a hydrophobic domain is used in a new and simplified method for preparing lysozyme and alpha-lactalbumins simultaneously from equine milk whey.
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PMID:Hydrophobic interaction of lysozyme and alpha-lactalbumin from equine milk whey. 150 92

An attempt has been made to design modified core-packing arrangements in bacteriophage T4 lysozyme. Alternative replacements of the buried residues Leu99, Met102, Val111 and Phe153 were selected using packing calculations and energy minimization. To test the design procedure, a series of multiple mutants was constructed culminating in the replacement L99F/M102L/V111I/F153L. These variants decrease the stability of T4 lysozyme by approximately 0 to 2 kcal/mol. The crystal structures of a number of the variants were determined. In the variant in which Val111 was replaced by Ile, alpha-helix 107-114 moved by approximately 1.5 A, breaking the hydrogen bond between the backbone carbonyl group of Thr109 and the backbone amide group of Gly113. This conformational change was not anticipated by the design procedure. Compensating interactions of magnitude up to 1.1 kcal/mol occur for some sets of mutations, while other sets display nearly additive stability changes. Within experimental error, the stability of the double mutant V111F/F153L is additive, with delta delta G different by only 0.1 kcal/mol from the sum of the two single mutants. The quadruple mutant L99F/M102L/V111I/F153L is destabilized by 0.5 kcal/mol, compared to delta delta G = -1.6 kcal/mol for the sum of the four single mutants. Multiple mutants show smaller overall structural changes from wild-type than M102L or V111I alone. Co-operative changes in structure and stability can be rationalized in terms of specific structural differences between single and multiple mutants. Genuine repacking of the hydrophobic core of T4 lysozyme with minimal effects on structure, stability and activity thus appears to have been achieved.
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PMID:Design and structural analysis of alternative hydrophobic core packing arrangements in bacteriophage T4 lysozyme. 156 71

High resolution crystal structures have been determined for six chicken-type lysozymes that were constructed to investigate putative intermediates in the evolution of the lysozymes of modern game birds (Malcolm, B. A., Wilson, K. P., Matthews, B. W., Kirsch, J. F., and Wilson, A. C. (1990) Nature 345, 86-89). The amino acid replacements include Thr-40----Ser, Ile-55----Val, and Ser-91----Thr, as well as combinations of these substitutions. Residues 40, 55, and 91 are buried within the core of chicken lysozyme. The replacements therefore involve the insertion and/or removal of methyl groups from the protein interior. The mutant proteins have normal activities, and their thermal stabilities span a range of 7 degrees C, with some variants more stable and some less stable than the naturally occurring forms. Comparison of the crystal structures shows the overall structures to be very similar, but there are differences in the packing of side chains in the region of the replacements. The x-ray coordinates were used to evaluate the repacking of side chains in the protein interior and to attempt to evaluate the contributions of the different energetic interactions toward the overall stability of each variant. The results illustrate how proteins can compensate for potentially destabilizing substitutions in different ways and underscore the importance of high resolution structural data if changes in protein thermostability due to changes in protein sequence are to be understood. The findings also suggest that protein stability can be increased by mutations that lower strain in the protein interior while maintaining total buried hydrophobic surface area.
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PMID:Structural and thermodynamic analysis of compensating mutations within the core of chicken egg white lysozyme. 158 60

The interaction between a high-affinity antibody, raised against a peptide incorporating the loop region of hen egg lysozyme (residues 57-84), and a peptide antigen corresponding to this sequence, has been probed by proton NMR. The two-dimensional correlated spectroscopy spectrum of the antibody-antigen complex shows sharp, well-resolved resonances from at least half of the bound peptide residues, indicating that the peptide retains considerable mobility when bound to the antibody. The strongly immobilized residues (which include Arg-61, Trp-62, Trp-63, and Ile-78) do not correspond to a contiguous region in the sequence of the peptide. Examination of the crystal structure of the protein shows that these residues, although remote in sequence, are grouped together in the protein structure, forming a hydrophobic projection on the surface of the molecule. The antibody binds hen egg lysozyme with only a 10-fold lower affinity than the peptide antigen. We propose that the peptide could bind to the antibody in a conformation that brings these groups together in a manner related to that found in the native protein, accounting for the high crossreactivity.
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PMID:Antigen mobility in the combining site of an anti-peptide antibody. 171 67

The structure of lysozyme from guinea hen egg white (GEWL), which differs from hen egg white lysozyme (HEWL) by ten amino acid substitutions, was investigated by nuclear magnetic resonance (NMR) spectroscopy. GEWL and HEWL were very similar to each other in their tertiary structure as judged from the profile of 1H-NMR spectra, pH titration, and an N-acetylglucosamine trisaccharide [(GlcNAc)3 binding experiment. However, we have noticed several characteristics which distinguish GEWL from HEWL. The signal of Trp 108 indole N1H of GEWL was shifted upfield by about 0.3 ppm when compared with that of HEWL, and its hydrogen exchange was faster than that of HEWL. The pKa values of Glu 35 estimated from the pH titration curve of Trp 108 indole N1H were different between GEWL and HEWL. From a careful examination of spectral changes caused by (GlcNAc)3 binding, the changes in the chemical shift values of Trp 28 C5H and Asn 59 alpha CH of GEWL were found to be slightly larger than those of HEWL. Ile 55 of HEWL is replaced by valine in GEWL. Such a replacement may affect the neighboring hydrogen bonding between the main chain C = O of Leu 56 and Trp 108 indole N1H, resulting in a change in the microenvironment of the substrate-binding site near Trp 108.
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PMID:1H-NMR study on the structure of lysozyme from guinea hen egg white. 179 91


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