The structural and functional alterations within the PSⅡ membrane from phosphatidylcholine reconstitution and Triton X_100 (TX_100) treatment were studied by using Fourier transform_infrared (FT_IR) spectroscopic technique and oxygen electrode. Phosphatidylcholine reconstitution showed no significant effect on the protein secondary structures of PSⅡ membrane but an increase of the rate of PSⅡ_mediated oxygen_evolution. The phosphatidylcholine lipids with different length of acyl chains displayed different capabilities to stimulate oxygen_evolution. In contrast, perturbation of the bilayer lipids by TX_100 resulted in obvious changes of the protein secondary structures within the PSⅡ membrane and in the loss of the PSⅡ_mediated oxygen_evolving activity. The results indicate the importance of membrane integrity in maintaining the stability of the photosynthetic membrane proteins.
