Lysozyme sources

In this article are discussed the results of those studies which have become available over the past 15 years and which permit some generalizations on the catalytic mechanism of glycoside hydrolases from widely differing sources and with different sugar and aglycon specificities. It will be seen that, with few exceptions, the data support a mechanism almost identical to that proposed by Phillips and his group for lysozyme. ... 

Lo gK values for Ca2+-protein complexes do not seem to vary greatly according to source. Thus the Ca2+ complex of pigeon lysozyme is ten times more stable than that of equine lysozyme,... 

Several proteins from different sources have been shown to maintain stability at high temperatures and NMR studies have been carried out in order to reveal their structures and/or to understand their activity. The most relevant references of a miscellany of thermostable proteins are reported in Table 3. Some of them such as bovine pancreatic trypsin inhibitor (BPTI), thermolysin and lysozyme have been widely studied as model systems in protein science. 

Lysozyme was isolated from human milk in 1961 by Jolles and Jolles, who believed that bovine milk was devoid of lysozyme. Milks of many species have since been shown to contain lysozyme and several have been isolated and characterized. Human and equine milks are an exceptionally rich source, containing 130 mg 1 1 (3000 times the level of bovine milk) and about 800 mg l-1, respectively (see Farkye, 1992). 

As discussed in section 8.2.5, lysozyme has been isolated from the milk of a number of species human and equine milks are especially rich sources. In view of its antibacterial activity, the large difference in the lysozyme content of human and bovine milks may have significance in infant nutrition. It is claimed that supplementation of baby food formulae based on cows milk with egg-white lysozyme gives beneficial results, especially with premature babies, but views on this are not unanimous. 

Active sites of enzymes and binding sites of proteins are a general source of instability because they contain groups that are exposed to solvent in order to bind substrates and ligands and so are not paired with their normal types of partners. Stability-activity trade-off is also seen with residues in the natural polypeptide inhibitor of barnase, barstar, that has evolved to bind as rapidly as possible to barnase,70 and also in the active site of T4 lysozyme.71... 

Proteins present in whole egg, yolk, and albumen (egg white) are excellent sources of nutrients, and they possess valuable functional properties. Shell eggs consist of 8-11% shell, 56-61% albumen, and 27-32% yolk. The solid content of albumen is about 11-13%, depending on the strain and on the age of the hens, and the solid content of yolk is about 52-53.5%. Albumen solids contain mainly protein, whereas lipids are the major constituents of egg yolk (92). Yolk can be separated by centrifugation into sedimented granules and a supernatant, plasma. The granules contain the major part of the yolk proteins. The main proteins in albumen and yolk are ovalbumin, ovotransferin, lysozyme, ovomucoid, ovomucin, and immunoglobulin Y (93). 

Figure 10.8. Gene identification by Procrustes. The nucleotide sequence encoding human lysozyme is used as a query sequence to identify its gene structure against known protein sequence (i.e., pig lysozyme protein). The output includes sequence aignment of the source (predicted translate) versus target protein (pig lysozyme).

Retrieve the amino acid sequences of type C lysozymes from twelve biological sources. Perform ClustalW multiple sequence alignment and WebPhylip parsimony analysis to draw a cladogram of the consensus tree. 

If we now suggest a correspondence between the formal model of FrBhlich and the dissipative subsytem(s) and the equilibrium system discussed in Section 3.1, one may consider the processes which are operative, including interactions with an external EM field, as depicted schematically in Fig. (7). No compelling experimental evidence exists that the equilibrium system made up of the ordinary aqueous dielectrics, Sections 2.3 to 2.7, shows the Bose-condensation which arises in the Frtfhlich theory. In fact, even systems of sufficient complexity to exhibit low-lying vibrational modes and structural subtlety to play a direct role in biochemical reactions at the interface between biochemical and biological processes [a-chymotrypsin (90-91), lysozyme (92 ) and DNA (93)], fail to show features not predicted by the methods of Section 2. Since collisional perturbations, even when non-reactive, will provide a source of the energy inputs, S, this implies the absence of non-linear terms (x=0,A=0), Eq. (14), for such systems. 

Sources of Naturally Occurring Evolutionary Variant Lysozymes... 

Due to size limitations, most enzymes present in plasma are not filtered into the urine but there are some exceptions (e.g., lysozyme) these will be increased in the urine if tubular function (and uptake of filtered protein) is decreased. In addition, if glomerular injury accompanies tubular injury leakage of larger molecular weight proteins may occur and plasma source enzymes that ordinarily would not be filtered may appear in urine. AST, LDH and IALP may thus appear in urine. 

Three enzymes with anti-HIV activity have been identified in the urine of women in the early months of pregnancy.9 Lee-Huang and her colleagues have now traced the anti-HIV activity to two ribonucleases and a lysozyme. The ribonucleases can digest RNA from a variety of sources, including cells infected with HIV-1. These proteins offer promise as anti-AIDS agents. The exact mechanism as to how these enzymes work needs to be worked out. 

Application and Principle The purpose of this procedure is to determine the lysozyme activity in purified lysozyme preparations derived from animal or microbial sources. The assay is based on the rate of decrease in absorbance at 450 nm, attributed to the lysis of Micrococcus lysodeikticus by lysozyme. The decrease in absorbance is measured using a UV/V spectrophotometer equipped to control the sample temperature at 25°. 

Standard Preparation Use a commercial reference standard lysozyme of a specified strength from an animal or microbial source in accordance with the origin of the preparation being measured. Measure 50 mg of the reference standard lysozyme into a 50-mL volumetric flask, and dissolve, with stirring, in approximately 25-mL of Sodium Phosphate Buffer Solution. Dilute to volume with Sodium Phosphate Buffer Solution, and mix thoroughly. If desired, freeze aliquots of this Standard Preparation for subsequent assays. Quantitatively transfer 3 mL of the Standard Preparation to a 100-mL volumetric flask, and dilute to volume with Sodium Phosphate Buffer Solution. 

Lipase (Microbial) Activity for Medium- and Long-Chain Fatty Acids, (S3)105 Lysozyme Activity, (S3)106 Maltogenic Amylase Activity, 804 Milk-Clotting Activity, 805 Pancreatin Activity, 805 Pepsin Activity, 807 Phospholipase A2 Activity, 808 Phytase Activity, 808 Plant Proteolytic Activity, 810 Proteolytic Activity, Bacterial (PC), 811 Proteolytic Activity, Fungal (HUT), 812 Proteolytic Activity, Fungal (SAP), 813 Pullulanase Activity, 814 Trypsin Activity, 814 Enzyme Assays, 786 Enzyme-Hydrolyzed (Source) Protein,... 

As one of the extensively investigated protein families, hundreds of lysozyme structures are deposited in the Protein Data Bank, including wild type from different sources and numerous mutants. Also available are the sfructures... 

Kinetic Orders for Lysis of Celts of Micrococcus luteus with Lysozymes from Various Sources"... 

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