Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lysozyme (rabbit kidney lysozyme) from the homogenate of rabbit kidney (Japanese white) was purified by repeated cation-exchange chromatography on Bio-Rex 70. The amino acid sequence was determined by automated gas-phase Edman degradation of the peptides obtained from the digestion of reduced and S-carboxymethylated rabbit lysozyme with Achromobacter protease I (lysyl endopeptidase). The sequence thus determined was KIYERCELARTLKKLGLDGYKGVSLANWMCLAKWESSYNTRATNYNPGDKSTDYGIFQ INSRYWCNDGKTPRAVNACHIPCSDLLKDDITQAVACAKRVVSDPQGIRAWVAWRNHCQ NQDLTPYIRGCGV, indicating 25 amino acid substitutions from human lysozyme. The lytic activity of rabbit lysozyme against Micrococcus lysodeikticus at pH 7, ionic strength of 0.1, and 30 degrees C was found to be 190 and 60% of those of hen and human lysozymes, respectively. The lytic activity-pH profile of rabbit lysozyme was slightly different from those of hen and human lysozymes. While hen and human lysozymes had wide optimum activities at around pH 5.5-8.5, the optimum activity of rabbit lysozyme was at around pH 5.5-7.0. The high proline content (five residues per molecule compared with two prolines per molecule in hen or human lysozyme) is one of the interesting features of rabbit lysozyme. The transition temperatures for the unfolding of rabbit, human, and hen lysozymes in 3 M guanidine hydrochloride at pH 5.5 were 51.2, 45.5, and 45.4 degrees C, respectively, indicating that rabbit lysozyme is stabler than the other two lysozymes. The high proline content may be responsible for the increased stability of rabbit lysozyme.
 ...
PMID:Purification, amino acid sequence, and some properties of rabbit kidney lysozyme. 236 54

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.
 ...
PMID:Important role of the proline residue in the signal sequence that directs the secretion of human lysozyme in Saccharomyces cerevisiae. 265 80

Computer graphics indicate that a steric hindrance exists between valine-110 side chain of human lysozyme (EC 3.2.1.17) and an acetyl group of a modified substrate that contains N6,O-diacetylmuramic acid. To alter the substrate specificity of human lysozyme to be effective on the modified substrate, we replaced the valine-110 residue with various amino acids by site-directed mutagenesis. One of the mutant proteins (valine residue replaced with proline:P110) was secreted in Saccharomyces cerevisiae as at least four components (P110-A, P110-B, P110-C, and P110-D) with different specific activities. Two components, P110-B and P110-D, were isolated in a pure form and structurally characterized. The results suggest that this mutation lowered the lytic activity against Micrococcus lysodeikticus by changing a local conformation of the catalytic site while keeping almost the same substrate binding sites. Our results also indicate that cis/trans isomerization of prolyl peptide bonds probably occurs in vivo and that the conformational change of protein as well as point mutations in genes might influence the molecular evolution of the protein.
 ...
PMID:Secretion in yeast of human lysozymes with different specific activities created by replacing valine-110 with proline by site-directed mutagenesis. 305 46

To investigate the relation between protein stability and the predicted stabilities of individual secondary structural elements, residue Pro86 in an alpha-helix in phage T4 lysozyme was replaced by ten different amino acids. The x-ray crystal structures of seven of the mutant lysozymes were determined at high resolution. In each case, replacement of the proline resulted in the formation of an extended alpha-helix. This involves a large conformational change in residues 81 to 83 and smaller shifts that extend 20 angstroms across the protein surface. Unexpectedly, all ten amino acid substitutions marginally reduce protein thermostability. This insensitivity of stability to the amino acid at position 86 is not simply explained by statistical and thermodynamic criteria for helical propensity. The observed conformational changes illustrate a general mechanism by which proteins can tolerate mutations.
 ...
PMID:Replacements of Pro86 in phage T4 lysozyme extend an alpha-helix but do not alter protein stability. 327 75

It is proposed that the stability of a protein can be increased by selected amino acid substitutions that decrease the configurational entropy of unfolding. Two such substitutions, one of the form Xaa----Pro and the other of the form Gly----Xaa, were constructed in bacteriophage T4 lysozyme at sites consistent with the known three-dimensional structure. Both substitutions stabilize the protein toward reversible and irreversible thermal denaturation at physiological pH. The substitutions have no effect on enzymatic activity. High-resolution crystallographic analysis of the proline-containing mutant protein (Ala-82----Pro) shows that its three-dimensional structure is essentially identical with the wild-type enzyme. The overall structure of the other mutant enzyme (Gly-77----Ala) is also very similar to wild-type lysozyme, although there are localized conformational adjustments in the vicinity of the altered amino acid. The combination of a number of such amino acid replacements, each of which is expected to contribute approximately 1 kcal/mol (1 cal = 4.184 J) to the free energy of folding, may provide a general strategy for substantial improvement in the stability of a protein.
 ...
PMID:Enhanced protein thermostability from site-directed mutations that decrease the entropy of unfolding. 347 97

The preferential interactions of lysozyme with solvent components and the effects of solvent additives on its stability were examined for several neutral osmolytes: L-proline, L-serine, gamma-aminobutyric acid, sarcosine, taurine, alpha-alanine, beta-alanine, glycine, betaine, and trimethylamine N-oxide. It was shown that all these substances stabilize the protein structure against thermal denaturation and (except for trimethylamine N-oxide for which interaction measurements could not be made) are strongly excluded from the protein domain, rendering unlikely their direct binding to proteins. On the other hand, valine, not known as an osmolyte, had no stabilizing effect, although it induced a large protein-preferential hydration. A possible explanation is given for the use of these substances as osmotic-pressure-regulating agents in organisms living under high osmotic pressure.
 ...
PMID:The stabilization of proteins by osmolytes. 397 11

The energy-transducing, Mg-Ca activated ATPase (ATP phosphohydrolase, EC 3.6.1.3) of E. coli is located on the inner surface of the cytoplasmic membrane. Antibody to purified ATPase has now been used to demonstrate that membrane vesicles as ordinarily prepared by the lysozyme-EDTA method consist of two distinct populations. About half the vesicles are everted, and thus readily agglutinated by antibody to ATPase, while half are right-side out. NADH oxidase (reduced NAD:O(2) oxidoreductase EC 1.6.99.3) activity is associated almost entirely with everted vesicles, while the ability to concentrate proline is a property of the right-side out vesicles. The results explain the failure of previous workers to observe the energization of membrane vesicles by oxidation of NADH.
 ...
PMID:Heterogeneity of membrane vesicles from Escherichia coli and their subfractionation with antibody to ATPase. 415 73

Four proteins, which have been designated A, B, C and D, have been purified from human parotid saliva. These proteins are the major constituents of parotid saliva which migrate rapidly to the anode in polyacrylamide electrophoresis at pH9.5. Gel filtration and polyacrylamide electrophoresis were employed in the purification procedures. After purification all four preparations were tested for homogeneity by electrophoresis at pH2.8 and 9.5, by isoelectric focusing in the pH range 3-10, by immunodiffusion, and by sedimentation in the analytical ultracentrifuge. None of the proteins showed significant activity in assays for amylase, acid and alkaline phosphatase, protease, lysozyme, ribonuclease, peroxidase, beta-glucuronidase, beta-galactosidase, iron-binding activity and esterase. No cross-reactions were detected with antisera specific for lactoferrin and 15 serum proteins. All four proteins were rich in glutamic acid, proline and glycine and were lacking completely the sulphur-containing amino acids. Proteins A and C contained no threonine or tyrosine. Carbohydrate could be demonstrated only in protein A at a concentration of 4% of the total protein.
 ...
PMID:Purification and partial characterization of four proteins from human parotid saliva. 500 93

On the basis of the known sequences and structures of myoglobin, and alpha and beta hemoglobin, a possible correlation between certain amino acids in the sequence and the location of the helical and non-helical parts of the structure is suggested. The presence in the sequence of four critical groups; proline, aspartic acid, glutamic acid, or histidine appears to be necessary (although the last three are not sufficient) for a helical disruption to form. Additional support for this correlation is obtained from analyses of proline replacement in mutant and variant proteins. A mechanism based on hydrophobic bonding is proposed as a rationale for the apparent behavior of these groups. On the basis of these rules and correlations, secondary structures can be proposed for lysozyme and tobacco mosaic virus protein which are consistent with several pieces of evidence.
 ...
PMID:The influence of amino-acid sequence on protein structure. 588 9

Effects of arginine on gramicidin S (GS) biosynthesis were investigated by growing Bacillus brevis ATCC 9999 in a synthetic medium consisting of 10 g fructose, 0.15 g l-proline, 1.3 g l-histidine, 1.3 g l-glutamine, 0.5 g L-methionine, 1 g L-phenylalanine and six mineral salts per liter. Supplement of 3 g/liter L-arginine to the medium, especially at the logarithmic phase of growth, enhanced the cell growth and GS production. Twice supplement of 3 g/liter arginine at the beginning and middle logarithmic phase of growth gave much more GS production than any once supplement, but the soluble GS synthetase extractable by lysozyme digestion was remarkably decreased. However, the decrease of enzyme by arginine seemed to be merely an apparent phenomenon, because GS-synthesizing ability of the cell was strongly enhanced by arginine and the enzyme which was not extracted by lysozyme digestion could efficiently be solubilized by ultrasonic homogenization. In the soluble fraction of cells grown in an arginine-added synthetic medium, no arginine was detected, but a large amount of ornithine was accumulated. When L-ornithine, instead of L-arginine, was added to the synthetic medium, cell growth and GS production was stimulated with increase of its concentration without decrease in the soluble enzyme activity.
 ...
PMID:Effect of arginine on gramicidin S biosynthesis by Bacillus brevis. 617 15


<< Previous 1 2 3 4 5 6 7 8 9 Next >>