Interactions Of Surfactants With Photosystem â…  From Spirulina Platensis

Surfactants play vital roles for the reseach of structure and functional of membraneproteins, a inappropriate surfactant could couse aggregate even denaturation. Photosyntheticmembrane protein–photosystem I and photosystem II, are two multi-protein-pigmentscomplexes, which will be more cautious in chose surfactants.On the basis of preliminary studies in our lab, in this study, we used photosyntheticmembrane protein complex PSI of Spirulina platensis as the object of study, by studying theinteraction of differents surfactants with PSI, from the follow three aspects: structuralintegrity, time stability, and the thermodynamics denaturation, systematically study themechanism of interaction of surfactants with PSI.Firstly, chose Triton X-100and DDM from traditional surfanctants as model ofsurfanctants. Triton X-100has an HLB value greater than DDM, hydrophilic strong, theinteraction with PSI are more severe. The main method of intecation of Triton X-100withPSI is to PSI complexes of chlorophyll off, causing the PSI thus accumulated betweensubunit protein backbone degeneration. The method of action of DDM and PSI solubilizedspread mainly base, however, increasing the concentration of DDM, their destructive effect isalso enhanced, as reflected in the increase in the concentration of DDM, PSI Tm valuedecreases.Secondly, phospholipids are a major component of the biomembrane, with some surfaceactivity. Different phospholipids according to different hydrophobic tail chains have differentself-assembled structures (micelles, mixed micelles, vesicles). Study the interaction ofphospholipids with PSI, and preliminary exploration of the PSI restructuring vesiclesapproach. Phospholipid micelle interactions with PSI approach to the solubilization andpigment dispersion shedding coexist. The mixed micelles time performance in terms ofthermodynamic stability and effective as a single surfactant DDM, more complex mode of action, which solubilization dispersion, phospholipids are also interact with the surface activeagent, the overall effect is poor. PSI restructuring vesicles method initially consideredsurfactant-mediated reorganization of the more successful.Finally, Peptide surfactants are a new class of surfactants, in order to further investigatethe peptide surfactant interaction mechanism with PSI, several peptides were designed andsynthesized. And systematically study the interaction of ac-A8D-OH, ac-A7D-OH andac-A6D-NH2with PSI. Found that the peptide surfactants can better maintain the structuralintegrity of PSI, in the thermodynamic stability also reflects the good results, and theac-A8D-OH in maintaining the thermodynamic stability of the PSI beyond DDM effect. Itsmain role is to suppress the aggregation of the PSI, to stabilize the effect of PSI. Confirmedthe peptide surfactant own enormous advantage in stabilizing of membrane proteins.In this study, the choice of surfactant in the course of the study of the PSI provides atheoretical foundation, laid the foundation for the PSI restructuring vesicles as well as thedesign of new peptide surfactant synthesis of guiding significance for the research andapplication of the PSI functional.