Lysozyme significance

A detailed examination of LN behavior is available [88] for the blocked alanine model, the proteins BPTI and lysozyme, and a large water system, compared to reference Langevin trajectories, in terms of energetic, geometric, and dynamic behavior. The middle timestep in LN can be considered an adjustable quantity (when force splitting is used), whose value does not significantly affect performance but does affect accuracy with respect to the reference trajectories. For example, we have used Atm = 3 fs for the proteins in vacuum, but 1 fs for the water system, where librational motions are rapid. 

Clinical experience has shown that certain types of lens materials are more prone to deposit problems. In general, lenses with negatively charged moieties at the surface accumulate greater amounts of lysozyme, the principal tear film protein (10). The introduction and use of disposable lenses make these deposits and their clinical problems less significant. 

Both types of mutations have been made in T4 lysozyme. The chosen mutations were Gly 77-Ala, which caused an increase in Tm of 1 °C, and Ala 82-Pro, which increased Tm by 2 °C. The three-dimensional structures of these mutant enzymes were also determined the Ala 82-Pro mutant had a structure essentially identical to the wild type except for the side chain of residue 82 this strongly indicates that the effect on Tm of Ala 82-Pro is indeed due to entropy changes. Such effects are expected to be additive, so even though each mutation makes only a small contribution to increased stability, the combined effect of a number of such mutations should significantly increase a protein s stability. 

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. 

In this paper, we study the stabihty of the carbonium ion intermediate formed in the cleavage of a glycosidic bond by lysozyme. It is found that the electrostatic stabilization is an important factor in increasing the rate of the reaction step that leads to the formation of the carbonium ion intermediate. Steric factors, such as the strain of the substrate on binding to lysozyme, do not seem to contribute significantly. 

Procarboxypeptidase A is activated by the removal of a peptide of some 64 residues from the N-terminus by trypsin.153 This zymogen has significant catalytic activity. As well as catalyzing the hydrolysis of small esters and peptides, procarboxypeptidase removes the C-terminal leucine from lysozyme only seven times more slowly than does carboxypeptidase. Also, the zymogen hydrolyzes Bz-Gly-L-Phe with kcsA = 3 s-1 and KM = 2.7 mM, compared with values of 120 s 1 and 1.9 mM for the reaction of the enzyme.154 In contrast to the situation in chymotrypsinogen, the binding site clearly pre-exists in procarboxypeptidase, and the catalytic apparatus must be nearly complete. 

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. 

Captopril-lysozyme did not significantly affect systemic blood pressure whereas an equimolar dose of captopril alone decreased blood pressure significantly. Whereas free captopril (5 mg kg ) completely prevented an angiotensin-I-induced blood pressure increase, an equimolar amount of captopril-lysozyme did not. However, in line with the direct ACE activity measurements in renal tissue and plasma, in captopril-lysozyme-treated rats the an-giotensin-I-induced blood pressure increase was lower than in untreated rats, suggesting that systemic activity was not fully prevented. 

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