Hen egg white

From hen egg white. Purified by solvent extraction and chromatography on alumina. Suspended in distilled water and kept frozen until used [Lee and Hunt J Am Chem Soc 106 7411 1984, Singleton et al. J Am Oil Chem Soc 42 53 7965]. For purification of commercial egg lecithin see Pangborn [J Biol Chem 188 471 7957]. 

Figure 3 Calculated X-ray diffuse scattering patterns from (a) a full molecular dynamics trajectory of orthorhombic hen egg white lysozyme and (b) a trajectory obtained by fitting to the full trajectory rigid-body side chains and segments of the backbone. A full description is given in Ref. 13.

Both attractive forces and repulsive forces are included in van der Waals interactions. The attractive forces are due primarily to instantaneous dipole-induced dipole interactions that arise because of fluctuations in the electron charge distributions of adjacent nonbonded atoms. Individual van der Waals interactions are weak ones (with stabilization energies of 4.0 to 1.2 kj/mol), but many such interactions occur in a typical protein, and, by sheer force of numbers, they can represent a significant contribution to the stability of a protein. Peter Privalov and George Makhatadze have shown that, for pancreatic ribonuclease A, hen egg white lysozyme, horse heart cytochrome c, and sperm whale myoglobin, van der Waals interactions between tightly packed groups in the interior of the protein are a major contribution to protein stability. 

Lysozyme is an enzyme that hydrolyzes polysaccharide chains. It ruptures certain bacterial cells by cleaving the polysaccharide chains that make up their cell wall. Lysozyme is found in many body fluids, but the most thoroughly studied form is from hen egg whites. The Russian scientist P. Laschtchenko first described the bacteriolytic properties of hen egg white lysozyme in 1909. In 1922, Alexander Fleming, the London bacteriologist who later discovered penicillin, gave the name lysozyme to the agent in mucus and tears that destroyed certain bacteria, because it was an enzyme that caused bacterial lysis. 

Hen egg-white lysozyme catalyzes the hydrolysis of various oligosaccharides, especially those of bacterial cell walls. The elucidation of the X-ray structure of this enzyme by David Phillips and co-workers (Ref. 1) provided the first glimpse of the structure of an enzyme-active site. The determination of the structure of this enzyme with trisaccharide competitive inhibitors and biochemical studies led to a detailed model for lysozyme and its hexa N-acetyl glucoseamine (hexa-NAG) substrate (Fig. 6.1). These studies identified the C-O bond between the D and E residues of the substrate as the bond which is being specifically cleaved by the enzyme and located the residues Glu 37 and Asp 52 as the major catalytic residues. The initial structural studies led to various proposals of how catalysis might take place. Here we consider these proposals and show how to examine their validity by computer modeling approaches. 

LD model, see Langevin dipoles model (LD) Linear free-energy relationships, see Free energy relationships, linear Linear response approximation, 92,215 London, see Heitler-London model Lysine, structure of, 110 Lysozyme, (hen egg white), 153-169,154. See also Oligosaccharide hydrolysis active site of, 157-159, 167-169, 181 calibration of EVB surfaces, 162,162-166, 166... 

Blake CC, Koeniz DF, Mair GA, North AC, Phillips DC, Sarma VR. Structure of hen egg-white lysozyme. A three-dimensional Fourier synthesis at 2 Angstrom resolution. Nature 1965 206 757-61. 

HDL Hi -dcnsity lipoprotein HEL Hen egg white lysozyme HEPE Hydroxyeicosapentanoic acid HEPES N-2-... 

Privalov et al (1989) studied the unfolded forms of several globular proteins [ribonuclease A, hen egg white lysozyme, apomyoglobin (apoMb), cytochrome c, and staphylococcal nuclease]. Unfolding was induced by 6 M Gdm-HCl at 10°C, heating to 80°C, or by low pH at 10°C with cross-links cleaved (reduction and carboxamidomethylation or removal of heme). The unfolded forms showed CD spectra (Fig. 27)... 

Squaraine dyes 10b, 39a, 39b, 41a, 41c, 41d, and 41e were used to measure different proteins such as BSA, HSA, ovalbumin, avidin from hen egg white, lysozyme, and trypsin (Fig. 12) [58]. It is difficult to predict correlations between the dyes structures and the affinity or sensitivity of the dyes for different proteins. All squaraine probes exhibit considerable fluorescence increases in the presence of BSA. Dicyanomethylene-squaraine 41c is the brightest fluorescent probe and demonstrates the most pronounced intensity increase (up to 190 times) in presence of BSA. At the same time, the fluorescent response of the dyes 10b, 39a, 39b, 41a, 41c, 41d, and 41e in presence of other albumins (HSA and ovalbumin) is, in general, significantly lower (intensity increases up to 24 times). Dicyanomethylene-squaraine 41a and amino-squaraines 39a and 39b are the most sensitive probes for ovalbumin. Dyes 41d, 10b, and 41e containing an A-carboxyalky I -group demonstrate sufficient enhancement (up to 16 times) in the presence of avidin. Nevertheless, the presence of hydrolases like lysozyme or trypsin has only minor effects on the fluorescence intensity of squaraine dyes. 

K. Koizumi, M. Tachibana, H. Kawamoto, and K. Kojima, Temperature Dependence of Microhardness of Tetragonal Hen-egg-white Lysozyme Single Crystals, Phil. Mag., 84,2961 (2004). 

We found that solutions of hen egg white lysozyme, bovine ribonuclease A (RNase A), or a 1 2 mol ratio of bovine carbonic anhydrase lysozyme formed opaque gels within 2 min when mixed with an equal volume of 20% NBF.25,26 Multi-protein tissue surrogates comprised of 50% w/v lysozyme and up to four additional proteins have also been formed (Fowler et al., unpublished results). After overnight fixation, the surrogates were firm and sliced easily with a razor blade for sampling. To determine the optimal... 

Refaee M,Tezuka T, Akasaka K, et al. Pressure-dependent changes in the solution structure of hen egg-white lysozyme./. Mol. Biol. 2003 327 857-865. 

Fig. 46. A left-handed spiral disulfide from hen egg white lysozyme, viewed from a direction similar to Fig. 45.

Fig. 11.14. Positive-ion ESI spectra of (a) hen egg white lysozyme and (b) the protein after ad(htion of 1,4-dithiothreitol. Reproduced from Ref. [88] by permission. American Chemical Society, 1990.

Beau has applied the DCC concept to a number of carbohydrate systems [13-16]. Carbohydrate-binding proteins often exhibit weak ligand interactions with millimolar dissociation constants, a quite different scenario to the enzyme-small molecule DCLs discussed thus far. The protein target initially chosen for study was hen egg-white lysozyme (HEWL), a glycosidase known to bind A-acetyl-o-glucosamine (d-G1cNAc) with... 

Figure 4. Essential features of the hydrolytic reaction catalyzed by hen egg white lysozyme. Notice that two nearby carboxyl groups should be able to stabilize the oppositely charged oxocarbonium ion intermediate.

Material. 3 X crystallized, dialyzed and lyophilized Grade 1 Hen Egg White Lysoz3mie was obtained from Sigma Chemical Company, and used without further purification. Purity of the protein was verified by both gel electrophoresis on acrylamide and chromatography on a column packed with anion exchange resin (Cl form) Sephadex DEAE. The sample showed a single peak in these analyses. 

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