Lysozyme spectrum

Figure 2.15 Typical near-UV absorbance spectra for proteins (lysozyme, ribonuclease) and nucleic acids (DNA, adenine, thymine). Notice how the lysozyme spectrum (6 Trp, 3 Tyr,...

Figure 12.9 MALDI-TOF mass spectrum of chicken egg-white lysozyme. The peak at 14,307.7578 daltons (amu) is due to the monoprotonated protein, M+H+, and that at 28,614.2188 daltons is due to an impurity formed by dimerization of the protein. Other peaks are various protonated species, M+H rH ...

The ROA spectra of partially unfolded denatured hen lysozyme and bovine ribonuclease A, prepared by reducing all the disulfide bonds and keeping the sample at low pH, together with the ROA spectra of the corresponding native proteins, are displayed in Figure 5. As pointed out in Section II,B, the short time scale of the Raman scattering event means that the ROA spectrum of a disordered system is a superposition of snapshot ROA spectra from all the distinct conformations present at equilibrium. Because of the reduced ROA intensities and large... 

The ROA spectra of native and prehbrillar amyloidogenic human lysozyme are displayed in Figure 7, together with a MOLSCRIPT diagram of the native structure. The ROA spectrum of the native protein is very similar to that of hen lysozyme (Fig. 5). However, large changes have occurred in the ROA spectrum of the prehbrillar intermediate. In particular, the positive 1340 cm-1 ROA band assigned to hydrated... 

It has been suggested recently that PPII helix may be the killer conformation in such diseases (Blanch et al., 2000). This was prompted by the observation, described in Section III,B, of a positive band at 1318 cm-1, not present in the ROA spectrum of the native state, that dominates the ROA spectrum of a destabilized intermediate of human lysozyme (produced by heating to 57°C at pH 2.0) that forms prior to amyloid fibril formation. Elimination of water molecules between extended polypeptide chains with fully hydrated 0=0 and N—H groups to form... 

Figure 2.10. The dependence of the position of the fluorescence spectrum maximum on excitation wavelength for 2,6-TNS in model media (a) and in complexes with proteins (b). (a) 2,6-TNS (3 x 10-s) M in glucose glass at 20°C (1), glycerol at +1°C (2), and 80% aqueous ethanol at 20°C (3). Excitation spectra are for glycerol (4) and 80% ethanol (5). (b) 2,6-TNS in complexes with / -lactoglobulin (1), tetrameric melittin (2), human serum albumin (3), and lysozyme (4) at 20°C. Excitation spectrum (5) is for human serum albumin.

A wide range of reversible adsorption kinetic rates was also found by TIR/FRAP for another protein, lysozyme, on a substrate with a different surface charge, alkylated silicon oxide.(61) It is possible that the wide range of rates results from a spectrum of surface binding site types and/or formation of multilayers of adsorbed protein. 

Fig. 11.21. Partial high-resolution ESI spectrum (R = 20,000) of a mixture of lysozyme and myoglobin. Reproduced from Ref. [103] by permission. John Wiley Sons, 1993.

Fig. 5. pH-Dependence of the (lysozyme + hexa-NAG)-Iysozyrae difference spectrum in 40% methanol at -20 C. 

At pH 10.2, the ultraviolet spectrum of lysozyme (Fig. 4) shows a sharp change of 280 and 288 nm bands after treatment with equimolar amounts of ozone. At this point, the lysozyme retained 40% of its activity. This behavior contrasted with the linear changes of 280 and 288 nm absorbance at pH 4.6 and 7.0. 

Figure 7. CD spectra of native (A) and ozonized lysozyme. Reproducibility of 0 for each spectrum xms within 5% indicated by vertical bar. Other details are given in Materials and Methods.

FIGURE 6.22 (a) The white-light image of lysozyme crystals, (h) The retrieved Raman spectrum of a crystalline lysozyme (top) and the retrieved Raman spectrum of lysozyme in solution (50 mg/mL hottom). 

As with X-ray crystallography, as the molecular weight of the molecule increases, the difficulties in performing structural studies increase. The lanthanide probe method has so far been applied in great detail to only one protein, lysozyme.5 The nuclei studied were protons. Because of the complexity of the protein nmr spectrum, it was necessary to apply techniques to resolve and simplify the spectrum and to assign the observed resonances to specific nuclei in the molecule. Table III lists some details of these methods, with references. 

Fig. 6. Part of the spectrum of lysozyme in the presence of the inhibitor (G1cNAc)3. At the concentration used, two resonances from 1 proton of trp 63 can be observed at 6.25 ppm and 6.05 ppm. These correspond to the resonance of this protein in the unbound and inhibitor-bound protein, respectively. The shift indicates that a conformational change occurs in the protein on binding (G1cNAc)3. At low temperature (c) the rate of the conformational change is slow on the time scale of the nmr experiment, but at higher temperature (a) the two resonances coalesce as the rate of the conformational change increases. At 45°C (b) exchange broadening occurs. The rate of the conformational change was measured from these data, and at 45°C is 20 sec-1 (see Ref. 22).

Figure 3-28 A15N - H HSQC spectrum of partially denatured 129-residue hen lysozyme. Boxes enclose the tryptophan indole region (upper left), the arginine side chain NE region (upper left), and a portion of the amide NH region (lower center and enlarged in the insert). Resonances of pairs of hydrogen atoms in side chain (Asn and Gin) amide groups are indicated by horizontal lines. From Buck et al.52i...

Using 20 mm tubes the sensitivity of natural abundance PFT 13C NMR can be increased drastically, as was demonstrated first for hen egg-white lysozyme. For example, the 13C NMR spectrum recorded under these conditions shows 22 signals for 28 non-protonated aromatic carbons, however, with a broad background arising from 59 proto-nated aromatic carbons [916]. 

Figure 25-29 shows an unusually well-resolved 13C nmr spectrum of the enzyme lysozyme (Table 25-3 and Figure 25-15) taken with proton decoupling. The closely spaced peaks on the left side of the spectrum are of the carbonyl groups. The peaks in the center are of unsaturated and aromatic carbons, while those on the right are of the aliphatic amino acid carbons. The five sharp resonances marked at about 110 ppm with arise from tryptophan carbons marked with in 22 ... 

Figure 25-29 Carbon-13 nmr spectrum at 45.3 MHz of lysozyme, 0.015M in water solution, taken with proton decoupling (Section 9-10L)...

Figure B3.5.8 Obtaining the corrected near-UV CD spectrum for hen egg white lysozyme. The protein and baseline spectra were collected using a 10-mm cylindrical cell and 0.5 mg/ml protein in 0.067 M phosphate buffer, pH 6.0. Instrument settings were 1-nm bandwidth, 0.2-nm step size, scan speed 2 nm/min, time constant 8 sec (scan speed x time constant = 0.27 nm). Protein solution and buffer were scanned once each. The spectra were smoothed, a sample of the fit being shown in the inset. Reproducibility of the instrument and of the state of the cell are demonstrated by the coincidence of the ellipticity above 300 nm. The corrected spectrum was obtained by subtraction, using the instrument software.

Figure B3.6.1 Rayleigh and Raman bands in fluorescent spectra, as seen in scans for solvent baseline and hen egg white lysozyme (EWL) solutions (solid lines). Circles represent the spectrum of EWL with baseline subtracted. Parameters EWL A2ao = 0.05 Xex = 280 nm excitation and emission bandwidths, 2.5 nm scan rate, 100 nm/min five scans accumulated. Spectra were measured using a Perkin Elmer LS50B fluorescence spectrometer.

Turnover numbers for some representative enzymes are listed in table 7.2. The enormous value of 4 x 107 mole-cules/s achieved by catalase is among the highest known the low value for lysozyme is at the other end of the spectrum. As is the case with Km, the relationship of kcal to individual rate constants, such as k2 and k3, depends on the details of the reaction mechanism. 

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