A light-harvesting chlorophyll a/b-protein complex (LHCP) was isolated directly from thylakoid mem-branes of marine green alga, Bryopsis corticulans, by two consecutive runs of liquid chromatography. The trimeric form...A light-harvesting chlorophyll a/b-protein complex (LHCP) was isolated directly from thylakoid mem-branes of marine green alga, Bryopsis corticulans, by two consecutive runs of liquid chromatography. The trimeric form of the light-harvesting complex has been obtained by sucrose gradient ultracentrifugation. The result of SDS- PAGE shows that the light-harvesting complex is composed of at least five apoproteins in which a protein with apparent molecular weight of about 31 kD was never found in the ma-jor light-harvesting complex (LHC Ⅱ) from higher plants. The isolated Bryopsis corticulans light-harvesting complex contains a specific carotenoid, siphonaxanthin, as well as chlorophyll (Chl) a, Chl b, neoxanthin and violaxanthin. Si-phonaxanthin which is present in the light-harvesting sipho-naxanthin-chlorophyll a/b-protein complex of Bryopsis corticulans is responsible for enhanced absorption in the blue-green region (530 nm). Efficient energy transfer from both siphonaxanthin and Chl b to Chl a in Bryopsis corticu-lans LHCP, which has similar absorption and fluorescence emission spectra to those of the lutein-chlorophyll a/b-protein of higher plants, proved that molecular arrangement of the light-harvesting pigments was highly ordered in the Bryopsis corticulans LHCP. The siphonaxanthin-chlorophyll a/b-pro- teins allow enhanced absorption of blue-green light, the pre-dominant light available in deep ocean waters or shaded subtidal marine habitats.展开更多
Photosystem Ⅱ membrane was reconstituted with phosphatidylcholine (PC) with different kinds of fatty acyl chains and the protection of PC to photosystem Ⅱ (PSⅡ) membrane during heat treatment was investigated using...Photosystem Ⅱ membrane was reconstituted with phosphatidylcholine (PC) with different kinds of fatty acyl chains and the protection of PC to photosystem Ⅱ (PSⅡ) membrane during heat treatment was investigated using oxygen electrode, variable fluorescence and circular dichroism (CD) spectroscopy. Heat treatment decreased the oxygen evolution rate and the F′v/Fm′ ratio of PSⅡ membrane and influenced CD spectra of PSⅡ membrane, but PC inhibited the effect of heat treatment on the oxygen evolution rate, the F′v/F′m ratio and CD spectra of PSⅡ membrane. The results indicate that PC can protect PSⅡ membrane against heat treatment and the alterations in the unsaturated fatty acid extent in PC can cause the changes of the protection ability.展开更多
文摘A light-harvesting chlorophyll a/b-protein complex (LHCP) was isolated directly from thylakoid mem-branes of marine green alga, Bryopsis corticulans, by two consecutive runs of liquid chromatography. The trimeric form of the light-harvesting complex has been obtained by sucrose gradient ultracentrifugation. The result of SDS- PAGE shows that the light-harvesting complex is composed of at least five apoproteins in which a protein with apparent molecular weight of about 31 kD was never found in the ma-jor light-harvesting complex (LHC Ⅱ) from higher plants. The isolated Bryopsis corticulans light-harvesting complex contains a specific carotenoid, siphonaxanthin, as well as chlorophyll (Chl) a, Chl b, neoxanthin and violaxanthin. Si-phonaxanthin which is present in the light-harvesting sipho-naxanthin-chlorophyll a/b-protein complex of Bryopsis corticulans is responsible for enhanced absorption in the blue-green region (530 nm). Efficient energy transfer from both siphonaxanthin and Chl b to Chl a in Bryopsis corticu-lans LHCP, which has similar absorption and fluorescence emission spectra to those of the lutein-chlorophyll a/b-protein of higher plants, proved that molecular arrangement of the light-harvesting pigments was highly ordered in the Bryopsis corticulans LHCP. The siphonaxanthin-chlorophyll a/b-pro- teins allow enhanced absorption of blue-green light, the pre-dominant light available in deep ocean waters or shaded subtidal marine habitats.
基金supported by the State Key Basic Research and Development Program(Grant No.G1998010100)the National Natural Science Foundation of China(Grant No.39890390).
文摘Photosystem Ⅱ membrane was reconstituted with phosphatidylcholine (PC) with different kinds of fatty acyl chains and the protection of PC to photosystem Ⅱ (PSⅡ) membrane during heat treatment was investigated using oxygen electrode, variable fluorescence and circular dichroism (CD) spectroscopy. Heat treatment decreased the oxygen evolution rate and the F′v/Fm′ ratio of PSⅡ membrane and influenced CD spectra of PSⅡ membrane, but PC inhibited the effect of heat treatment on the oxygen evolution rate, the F′v/F′m ratio and CD spectra of PSⅡ membrane. The results indicate that PC can protect PSⅡ membrane against heat treatment and the alterations in the unsaturated fatty acid extent in PC can cause the changes of the protection ability.
