Research On Photoprotective Properties Of Photosystem I Core Complexs From Bryopsis Corticulans

Photosynthesis is the most important reaction in the earth,it transfer optical energy into chemiscal energy which is stored in organics. Photosynthesis provides material guarantee for the life on the earth. Photosynthesis occurs in the chloroplast of eucaryon and Photosynthetic lamellar of photosynthetic bacteria. Energy transferring and inversion of Photosynthesis are mainly depend on chlorophyll proteins. The chlorophyll proteins are photosystem Ⅱ, photosystem I,cytochrome b6f and ATPase.Photosystem I(PSI) is one of the chlorophyll proteins which participate in primary reaction of photosynthesis.PSI of eucaryon is composed of core complex and light harvesting complex I.(LHCI);Generally,there are aboat14subunits in the core where the primary reactin center locates in;LHCI’s main function is to harvest light and transfer the energy to chlorophylls of the reaction center step by step.In this paper,we take Bryopsis corticulans as experimental material.We have discovered the methods for purification of PSI and PSI-core.Almost all studied materials have β-carotene,however, Bryopsis corticulans has α-carotene.So studying the PSI-core and LHCI may reveal different photoprotection mechanism and energy transferring process.The main research achievements in this paper are as follows:1. The creation of the methods for purification of PSI subcomplexsWe purify PSI from Bryopsis corticulans which belongs to green algae category.Because that Bryopsis corticulans chloroplasts have a lot of starch and the PSI have a larger LHCI than plant PSI, it’s difficult to ensure the purity (ATPase contamine) and the integrity at one time.that is,there is some difficulties to purify PSI.In this paper,we solubilize thylakoid membrane by β-DDM,then subject the mixture on the sucrose density gradient. After3h’centrifugation,PSI appeared as one band in the gradient.A second ultracentrifugation method can be used to get more pure PSI complex.We solubilize the PSI complex by β-DDM and ZW3-16,then inject the mixture on the sucrose density gradient.After16h’centrifugation,we get the PSI-core band on the gradient.2. The photoprotecting mechanism of Bryopsis CorticulansCarotenes play a important role in the photoprotection of plants and alga. Acorrding to the study of pigments composition of Bryopsis corticulans by faculty of Kuang’group,there are no β-carotene but a-carotene in the PSI complex.So,we guess that there may be a different energy transferring and photoprotection mechanism.By the methods of absorbance spectral of room tempreture,fluorence spectral in77K,and nanosecond flash photolysis,we study the mechanism.we found that, though there are α -carotenes in the Bryopsis corticulans instead of β-carotenes,Bryopsis corticulans have the similar mechanism of protection.3. LHCI of PSI in the Bryopsis corticulansThe LHCI of plants PSI have four subunits, while in the green algae Chlamydomonas,there are nine subunits.We find that,in the Bryopsis corticulans PSI,there are eight lhca subunits.