Lysozyme adsorption kinetics

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. 

Adsorption kinetics and isotherms. The rate of protein adsorption onto solids is usually much slower than that predicted from the diffusion theory [85-87]. For various protein-adsorbent systems, the period of time required to obtain maximum adsorption ranges, as a rule, from several tens of minutes [10,12,14,88] to several hours [11,12,14,63,65,66,79,81,84,89,90]. More rarely, the adsorption terminates after several minutes [67,91] or continues for 24 h and longer [92,93], It cannot be excluded, however, that the initial adsorption rates should be transport limited, as has been shown by Norde et al. [94] for adsorption of lysozyme, RNase, and myoglobin on glass. The importance of diffusion is also obvious at the first step of adsorption from protein mixtures [95]. In this case the interface accommodates initially the protein molecules with the largest diffusion coefficients, and afterwards these molecules may be displaced by other molecules with higher affinity to the surface. 

Abstract Spread monolayers of /(-lactoglobulin and bovine serum albumin and adsorbed films of lysozyme and /i-lactoglobulin were studied at the oil (n-tetradecane) -water (O-W) and air-water (A-W) interfaces. In general, spread monolayers were more expanded at the O-W interface than at the A-W interface. Desorption rates from monolayers increased greatly with increasing interfacial pressure, n, but were still quite low until typical equilibrium adsorption tc were exceeded. Desorption rates as a function of the energy barrier to desorption were similar at both types of interface. Adsorption kinetics of lysozyme at the A-W interface were... 

The adsorption experiments with lysozyme indicate that the trough method may be a way of obtaining the adsorption kinetics of other globular proteins, including )S-lactoglobulin. This is necessary for the complete analysis of the response of an adsorbed film to a dilatational deformation. In order to use the method, however, reliable values of n and A area are required. 

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. 

Singla et al. [19] examined the adsorption kinetics of wild type and two synthetic stability mutants of T4 phage lysozyme at silanized silica surfaces. Substitution of the isoleucine at amino acid position three with cysteine (13 C) and tryptophan (13W) rendered such mutants with a higher and lower thermal stability, respectively. It was found that the I3W mutant, characterized by a lower structural stability, would more readily undergo a stmctural change at the interface. Moreover, such a mutant showed more resistance to elution by DTAB than either the wild type or 13 C mutant, simply by forming a more tightly bound conformation (adsorbed state) with the adsorbent. 

Anand, K., Damodaran, S. (1995). Kinetics of adsorption of lysozyme and bovine serum albumin at the air/water interface from a binary mixture. Journal of Colloid and Interface Science, 176, 63-73. 

The kinetics of protein adsorption at an interface can be measured by monitoring surface concentration and surface pressure i.e. depression of surface tension (V) as a function of time (3/7). -casein is more surface active than serum albumin or b-Lg and much more so than lysozyme. This reflects not only the rate of diffusion of the native protein to the interface, but also its molecular flexibility and amphipathic nature (15,17,22). 

Detailed experimental data on the rate constants associated adsorption/desorption kinetics or conformational interconversion of different forms of a protein chromatographed on -alkylsilicas are currently very sparse. The kinetics of de-naturation of several proteins on n-butyl-bonded silica surfaces have been reported. Fig. 18 for example, shows the dependence of peak area on the incubation time of lysozyme on the bonded phase surface, from which rate constants for interconversion on the stationary phase, i.e. were derived [63]. The graphical representations derived from quantitative numerical solutions of the probabihty distributions... 

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