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)

A complete and authentic picture of the qualitative and quantitative composition of the milk of Homo sapiens is presented. Older original references are reexamined along with data prublished during the last 2 decades. Mature human milk is made up of 3%-5% fat, 0.8%-0.0% protein, 6.9%-7.2% carbohydrate calculated as lactose, and 0.2% mineral constituents expressed as ash. The energy content is 60-75 kcal/100ml. Protein content is considerably higher and carbohydrate content lower in colostrum than in mature milk. Fat content does not vary consistently during lactation but exhibits large diurnal variations and increases during the course of each nursing. Race, age, parity, or diet fail to have a great affect on milk composition. There is no consistent compositional difference between milks from the 2 breasts unless 1 breast is infected. The principal proteins of human milk are a casein homologous to bovine B-casein, a-lactalbumin, lactoferrin, immunoglobulin IgA, lysozyme, and serum albumin. Lactose is the principal sugar of human milk. Human milk fat is characterized by high contents of palmitic and oleic acids, the former heavily concentrated in the 2-position and the latter in the 1- and 3-positions of the triglycerides. The principal mineral constituents of human milk are Na, K, Ca, Mg, P, and C1. About 25% of the total nitrogen of human milk represents nonprotein compounds. These include urea, uric acid, creatine, creatinine, and a large number of amino acids.
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PMID:The composition of human milk. 39 66

Galactose, lactose, N-acetylgalactosamine, N-acetylglucosamine and fibrinoglycopeptides were bound to lysozyme by different linkages. These glycosylated lysozymes were tested as N-acetylneuraminic acid acceptors using particular sialytransferase preparations from frog and bovine liver and from bovine and porcine submandibular glands. Desialylated fetuin served as reference compound. Galactose residues of desialo-fetuin and lysozyme-lactose are sialylated by all four sialytransferases tested, galactose bound to lysozyme via a phenylazo group is inactive with the enzyme from bovine submandibular gland, and galactose bound directly to lysozyme serves as substrate only for the frog liver sialytransferase. Lysozyme-phenylazo-N-acetylgalactosamine is active only with the sialytransferase from bovine sumbandibular gland. N-Acetylglucosamine derivatives of lysozyme are inactive with all sialytransferases tested. These observations are discussed in the light of the natural substrates for the sialytransferases investigated.
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PMID:The specificity of sialytransferases using glycosylated lysozyme derivatives as substrates. 51 Oct 94

The milk which drips from the opposite breast during breast feeding is used in some centres for feeding premature babies, yet there is little scientific information on the biology of this secretion. Drip breast milk (DBM) differs from expressed breast milk (EBM), both in its contents and in the change in its composition over the period of lactation. The fat concentration and energy value of DBM are low, compared with levels reported for EBM: protein, fat, sodium and energy value in DBM fall with the duration of lactation, whereas magnesium and calcium rise, and lactose, potassium osmolality and lysozyme remain constant. The milk fat content of DBM produced by individual donors is linearly related to the daily volume of DBM produced. Studies on 477 women admitted to the Oxford General Practice Obstetric Unit over 1 yr showed that, of the 75% who were lactating successfully 2 wk after delivery, 19% were producing DBM by 2--4 wk. Women who produced DBM did not differ in age or parity from those lactating women who did not, and their babies did not differ in birthweight, gestation, centile or sex. The suitability of DBM as a food for premature infants is discussed.
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PMID:The biology of human drip breast milk. 57 25

Reaction of alpha-lactalbumin at pH 7 in aqueous solution with either 2-hydroxy-5-nitrobenzylbromide or N-bromosuccinimide yields derivatives in which only 2 of the 4 tryptophan residues are modified. All 4 residues of tryptophan are modified under the similar conditions in 8 M urea. Structural analysis of the modified derivatives revealed that tryptophans 26 and 118 are the sole reactive residues and that tryptophan 118 reacts more rapidly than tryptophan 26. The fluorescence of alpha-lactalbumin modified to varying extents with N-bromosuccinimide indicates that tryptophan 118 is exposed to solvent whereas tryptophan 26 is in a more hydrophobic environment. The chemical reactivities and fluorescence properties of tryptophans 26 and 118 are consistent with the proposed conformations of alpha-lactalbumin based on its similarity with egg white lysozyme. The kinetic properties of both derivatives of alpha-lactalbumin containing up to 2 modified residues indicate that each derivative has decreased affinity for the galactosyltransferase but that at saturating concentrations, Km and Vmax for lactose synthesis are unchanged from those of native alpha-lactalbumin.
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PMID:Modification of bovine alpha-lactalbumin with N-bromosuccinimide and 2-hydroxy-5-nitrobenzylbromide. 80 37

The protective effect of breast feeding against infections is well proved by the experiences in underdeveloped countries and in industrial countries as well as shown by numerous investigations in several populations of different social structure. Various factors are meant to be responsible for this special property of human milk, the importance of which is to be discussed. The lysozyme and the lactoferrin are two different antibacterial factors well known since a long time, the former of which is mainly directed against grampositive organisms and against gramnegative ones only under special conditions. Lactoferrin is effective against E. coli and Staphylococcus as well. The neuraminic acid of which the human milk contains a larger quantity than cow's milk also inhibits the growth of E. coli and Staphylococcus. A further factor consisting of isomers of linoleic acid protects mice against lethal Staphylococcus - infections. The most important antibacterial principles of human milk are meant to be specific immunoglobulins, specially secretory IgA. The immunoglobulins are mainly important for the young baby in the early stage of life. The fecal bifidusflora specific for the breast-fed infant is also meant to be protective against several infections. The factors of human milk provoking this special kind of intestinal flora are to be discussed. In the artificial-fed infant bifidus flora like that of breast-fed one can arise by application of lactulose. Nowadays, bifidus-flora can probably be obtained by application of beta-lactose. It is suggested, that infants with bifidus-flora provoked by one of this means are protected against intestinal infections. The results of all investigations on mother's milk lead to the conclusion, that breast-feeding is the optimal kind of alimentation in the first time of life, not only concerning the composition of the food, but concerning protection against infections.
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PMID:[The protective effect of human milk against infections and its potential causes (author's transl)]. 82 95

1. Tests for glycosidases were performed in homogenates of Brachionus plicatilis. 2. Hydrolytic activity was detected with the following substrates: (a) with synthetic substrates (NP = 4-nitrophenyl): NP-alpha- and NP-beta-D-glucopyranoside, NP-alpha- and NP-beta-D-galactopyranoside, NP-N-acetyl-beta-D-glucosaminide, NP-N-acetyl-beta-D-galactosaminide, NP-alpha- and NP-beta-D-mannopyranoside and NP-alpha-L-fucopyranoside; (b) with disaccharides: sucrose, maltose, trehalose, isomaltose, cellobiose, gentiobiose and lactose; (c) with polysaccharides: laminarine, carboxymethyl-cellulose, avicel, Micrococcus luteus (for lysozyme) and 4-nitrophenyl-alpha-D-maltoheptaoside (for amylase). 3. The pH dependence of the glycosidase activities was determined. 4. The distribution of enzyme activities within fractions from the homogenate was studied in order to localize them within the cell. 5. Proteins from Brachionus homogenate were separated by SDS-gel electrophoresis and the positions of the following glycosidase activities were detected by assays performed on the gels (estimated molecular weights in parentheses): alpha-glucosidase (250,000); beta-glucosidase (200,000); beta-galactosidase (70,000); N-acetyl-beta-glucosaminidase (60,000).
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PMID:Glycosidases in Brachionus plicatilis (Rotifera). 232 73

The CPL-1 lysozyme coded by the pneumococcal phage Cp-1 has been overproduced in Escherichia coli under the control of a modified lipoprotein lactose promoter. This result has provided the conditions to analyse the CPL-1 secondary structure by circular dichroism (CD). The CD spectra recorded in the far-ultraviolet region showed, at neutral pH, two minima at 210 nm and 230 nm and a shoulder at 217 nm, whereas two bands at 260 nm and 295 nm were observed in the near-ultraviolet region. It has been estimated, by using the CDPROT program, that the protein is composed of 19% alpha-helix, 32% beta-sheet, 28% beta-turn and 21% random coil. Minor changes in the CD spectra were detected either when the pH was varied over 6-10 or when the ionic strength was increased to 1 M NaCl. Choline, a well known modulator of the enzyme activity that is present in the pneumococcal cell wall, induced remarkable changes in the intensities of the bands at 210, 230 and 295 nm, with the appearance of an unusual positive band at 225 nm. The conformational change was reversible and correlated with the competitive inhibitory effect of choline on the lysozyme activity, supporting, by a new and direct experimental approach, the basic role of choline in the recognition of the cell wall substrate. The analyses of the secondary structure prediction and the CD data reported here are compatible with the two-domain structure of CPL-1 reinforce our hypothesis that the C-terminal region is directly involved in the binding of the enzyme to the pneumococcal teichoic and lipoteichoic acids.
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PMID:Structural studies of the lysozyme coded by the pneumococcal phage Cp-1. Conformational changes induced by choline. 240 66

Fourier-transform infrared spectroscopy was used to characterize the interaction of stabilizing carbohydrates with dried proteins. Freeze-drying of trehalose, lactose, and myo-inositol with lysozyme resulted in substantial alterations of the infrared spectra of the dried carbohydrates. In the fingerprint region (900-1500 cm-1), there were large shifts in the frequencies of bands, a decrease in absorbance, and a loss of band splitting. These effects mimic those of water on hydrated trehalose. Bands assigned to hydroxyl stretching modes (around 3350 cm-1) were decreased in intensity and shifted to higher frequencies in the presence of the protein. In complementary experiments, it was found that dehydration-induced shifts in the positions of amide I and amide II bands for lysozyme could be partially and fully reversed, respectively, when the protein was freeze-dried in the presence of either trehalose or lactose. In addition, the carboxylate band, which was not detectable in the protein dried without the sugar, was apparent when these sugars were present. myo-Inositol was less effective at shifting the amide bands, and the carboxylate band was not detected in the presence of this carbohydrate. Also tested was the concentration dependency of the carbohydrates' influence on the position of the amide II band for dried lysozyme. The results showed that the ability of a given concentration of a carbohydrate to shift this band back toward the position noted with the hydrated protein coincided, at least in the extreme cases, with the capacity of that same level of carbohydrate to preserve the activity of rabbit skeletal muscle phosphofructokinase during freeze-drying.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An infrared spectroscopic study of the interactions of carbohydrates with dried proteins. 252 52

Fusobacterium nucleatum expresses lectinlike adherence factors which mediate binding to a variety of human tissue cells. Adherence is selectively inhibited by galactose, lactose, and N-acetyl-D-galactosamine. In this study, adherence of F. nucleatum to human peripheral blood polymorphonuclear neutrophils (PMNs) was investigated. The results indicated that the fusobacteria adhered to live and metabolically inactivated or fixed PMNs. Adherence of F. nucleatum resulted in activation of PMNs as determined by PMN aggregation, membrane depolarization, increased intracellular free Ca2+, superoxide anion production, and lysozyme release. Transmission electron micrographs showed that F. nucleatum was phagocytized by the PMNs. Microbicidal assays indicated that greater than 98% of F. nucleatum organisms were killed by PMNs within 60 min. Adherence to and activation of PMNs by F. nucleatum were inhibited by N-acetyl-D-galactosamine or lactose greater than galactose, whereas equal concentrations of glucose, N-acetyl-D-glucosamine, mannose, and fucose had little or no effect on F. nucleatum-PMN interactions. Pretreatment of the fusobacteria with heat (80 degrees C, 20 min) or proteases inhibited adherence to and activation of PMNs, but superoxide production was also stimulated by heated bacteria. The results indicate that interaction of F. nucleatum with PMNs is lectinlike and is probably mediated by fusobacterial proteins which bind to other human tissue cells. Adherence of F. nucleatum to PMNs in the absence of serum opsonins, such as antibodies and complement, may play an important role in PMN recognition and killing of F. nucleatum in the gingival sulcus and in the subsequent release of PMN factors associated with tissue destruction.
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PMID:Lectinlike interactions of Fusobacterium nucleatum with human neutrophils. 255 9

Refolding and disulfide bond formation in reduced denatured bovine alpha-lactalbumin is shown to be Ca2+-dependent. Whereas in the absence of Ca2+ only about 2% of the native active protein is regenerated, in the presence of Ca2+, almost quantitative renaturation is obtained. A close coupling between Ca2+-binding and native disulfide bond formation is also indicated by spontaneous disulfide scrambling in the apoprotein in the presence of low concentrations of thiols. This phenomenon is not found in other disulfide-containing proteins including the homologous chicken lysozyme. It is proposed that the alpha-lactalbumin Ca2+-binding site has the in vivo function of imposing Ca2+ regulation on the folding of nascent alpha-lactalbumin and thereby on lactose synthesis.
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PMID:Calcium regulates folding and disulfide-bond formation in alpha-lactalbumin. 278 42


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