Comparative Adsorption of Native and Denatured Egg-White, Human, and T4 Phage Lysozymes at the Air-Water Interface

✍ Scribed by Shuqian Xu; Srinivasan Damodaran

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 499 KB
• Volume: 159
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1993.1304

✦ Synopsis

The kinetics of adsorption of ({ }^{14} \mathrm{C})-labeled native, partially denatured, and fully denatured egg-white, human, and (\mathrm{T}_{4}) phage lysozymes at the air-water interface has been studied using the radiotracer method. The surface concentration of the native and partially denatured lysozymes exhibited negative adsorption during the first (50-100 \mathrm{~min}) of adsorption, followed by a lag period and a rapid positive adsorption at the interface. No negative adsorption was observed in the cases of fully denatured lysozymes and (\beta)-casein. The apparent diffusion coefficients of the three native lysozymes were at least an order of magnitude lower than their diffusivity in solution. However, the apparent difiusion coeflicient values increased as the lysorymes were progressively denatured. In contrast, the diffusion coeflicient of native (\beta)-cascin was about twofold greater than its solution diffusivity. To account for these observations, a general mechanism for protein adsorption at interfaces is proposed, which invokes that it is the chemical potential gradient emanating from interaction of the interfacial force field with various molecular potentials, such as the hydrophoboc, electrostatic, hydration, and conformational (entropic) potentials, rather than concentration gradient alone, that acts as the driving force for adsorption of proteins at interfaces. 1993 Academic Press, inc.