Lysozyme, surface adsorption charge

Compared with the qualitative methods discussed above, surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) are two instrumentation methods for quantitative evaluation of protein adsorption that are highly sensitive and examine adsorption kinetics. For example, the adsorption of two proteins (hbrino-gen and lysozyme) with different charges and sizes on a PNIPAAm hhn was compared using SPR, and the results indicated that the effect of temperature on adsorption (amount and kinetics) is different (Teare et al., 2005). In another report, QCM was employed to analyze the kinetics of bovine serum albumin (BSA) adsorption on P(NlPAAm-co-di(ethylene glycol) divinyl ether) cross-linked hhns at different temperatures (Alf, Hatton, Gleason, 2011). Above the LCST, a simple monolayer of BSA was adsorbed on the surface, whereas below the LCST, there are two processes involved initial protein adsorption onto the surface followed by protein diffusion into the swollen hydrogel matrix. 

The surface adsorption behavior of lysozyme with an anodic end potential of 1.0 V over the temperature range 273-343 K (Fig. 21) showed a steady increase of surface charge density with temperature. Similar results were obtained with ribonuclease A, as shown in Fig. 22. Negligible... 

The effect of pH on the protein adsorption on CMK-3 was also investigated [152], The monolayer adsorption capacities obtained under various pH conditions are plotted in Figure 4.12, where the maximum adsorption was observed in the pH region near the isoelectric point of lysozyme (pi of about 11). Near the isoelectric point, the net charges of the lysozyme molecule are minimized and would form the most compact assembly. A similar pH effect was also seen in the adsorption of cytochrome c on CM K-3. Although the nature of the surface of mesoporous silica and... 

Fig. 6. Plateau-values, I"P1 /mg m 2, of adsorption isotherms of lysozyme (LSZ), ribonuclease (RNase), a -lactalbumin (aLA), calcium-depleted (X -lactalbumin (aLA(-Ca )) and bovine serum albumin (BSA) on hydrophobic polystyrene (PS) and hydrophilic hematite (a — Fe203) and silica (Si02) surfaces. An indication of the charge density of the surface is given by the zeta-potential, C, and of the proteins by + and signs. Ionic strength 0.05 M T = 25°C. (Derived from Currie et al. 2003).

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. 

Two experimental results indicate that there is an adsorption energy barrier related to the interfacial pressure. First, the presence of an energy barrier becomes evident only after an interfacial pressure of 0.1 mN m-1 is attained (Table II). In the second experiment, different compounds were spread at the air/water interface and the rate of adsorption of pepsin and lysozyme were measured under conditions where charge effects were minimized (MacRitchie and Alexander, 1963a). It was found that the rates of adsorption for these proteins were independent of the nature of the surface film and depended only on the surface pressure. 

Rezwan, K., Meier, L.P.. and Gauckler, L.J., Lysozyme and bovine serum albumin adsorption on uncoated sihca and AIOOH-coated sihca particles The influence of positively and negatively charged oxide surface coatings. Biomaterials, 26, 4351,... 

Figure 7 Correlation of plateau values with protein surface hydrophobicity (from hydrophobic interaction chromatography data) for the adsorption of egg-white lysozyme ( ), bovine pancrease ribonuclease (A), a-lact-albumin (x), sperm whale myoglobin ( ), and superoxide dismutase ( ) on negatively charged polystyrene in 50 mM KCI at 25°C and pH equal to pi of each protein. (From Ref. 17. Reprinted with permission.)...

The step-adsorption isotherms for both hen and human lysozymes on hydrophobic (DDS), negatively-charged (silica), and positively-charged (APS) surfaces are presented in figure 3. Since the TIRIF quantitation scheme used assumes that the quantum yield of the protein does not change upon adsorption (an assumption we are currently trying to test), the actual amount adsorbed may differ from that presented in the figure if this assumption proves to be invalid for these proteins (see discussion below). 

The amorphous hydrous oxide of Cr(III) (HCO) has been studied extensively as a source of sols of uniform particle size and shape [30] and as an electrophoresis standard [31] however, it has not been studied extensively as an adsorbent of metal ions. Sen [32] found that chromium (III) hydroxide generally has a larger adsorption capacity than the hydroxides of other triple-charged metals. Simon et al. [33] reported that coprecipitation of Cd(II) with chromium(III) hydroxide removed Cd(Il) from solution at a pH that was two units lower than that obtained using aluminum(III) hydroxide as the coprecipitating hydroxide. Similarly, Packter and Panesar [34] used Cr(III) and Mg(II) mixtures to show enhanced removal for both ions compared with the individual metal systems. HCO has also been used as an adsorbing surface to effectively adsorb the proteins ovalbumin, y-globulin, and lysozyme as a separation technique [351. 

FIGURE 15.22 Competitive adsorption between lysozyme (LSZ), ribonuclease (RNase), myoglobin (MGB) and a-lactalbumin (a LA) on surfaces of apolar polystyrene (PS) and polar iron oxide (a-Pe203). The + and - signs indicate the electrical charge of the components. The solutions supplied to the sorbent surfaces contain equal concentrations (0.3 g dm ) of each of the proteins. (Adapted from Arai, T. and Norde, W., Colloids Surfaces, 51,17, 1990.)... 

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