Roles of γ-Globulin in the Dynamic Interfacial Behavior of Mixed Dipalmitoyl Phosphatidylcholine/γ-Globulin Monolayers at Air/Liquid Interfaces
✍ Scribed by Chien-Hsiang Chang; Shin-De Yu; Ta-Ko Chuang; Ch-Nan Liang
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 113 KB
- Volume
- 227
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
This study investigated the roles of γ -globulin in the dynamic interfacial behavior of dipalmitoyl phosphatidylcholine (DPPC)/ γ -globulin monolayers at air/liquid interfaces at 25 • C. The surface tension behavior demonstrated that γ -globulin had a large adsorption time scale. Moreover, the surface pressure-area hysteresis behavior of adsorbed γ -globulin monolayers suggested that no significant desorption occurred during the compression stage, and the respreading of γ -globulin molecules at the interface during the expansion stage was slow. From the hysteresis behavior of adsorbed γ -globulin monolayers with spread DPPC molecules, it was found that γ -globulin molecules were expelled from the interface as DPPC molecules were in a condensed state. The squeeze-out of γ -globulin molecules seemed to induce the loss of DPPC molecules at the interface with the extent depending on the initial γ -globulin surface concentration. Furthermore, the expelled γ -globulin molecules reentered the monolayer and participated in the surface pressure increase during the following expansion stage. The exclusion of γ -globulin associated with the removal of DPPC during monolayer compression and the re-entry of γ -globulin during subsequent monolayer expansion represented a mechanism for DPPC depletion and γ -globulin enrichment at the interface, which may explain the inhibitory effect of certain proteins on the surface activity of DPPC.