摘要
光合作用研究中,对于个体发育过程中类囊体膜蛋白结构和功能的变化所知甚少,其中的一个限制因素是能否纯化得到大量高活性的稳定且均一的膜蛋白。作者以条斑紫菜(Porphyra yezoensis)2个不同发育阶段(孢子体和配子体)作为研究对象,分离得到了孢子体和配子体的类囊体膜,在不同的温度、光强和pH下,对其类囊体膜上的光系统活性进行了研究。结果表明,孢子体和配子体的PSI活性均随温度和光强的升高而呈现一个先升高后降低的趋势,在温度18℃,光强为2 320 lx时具有最高的PSI活性。而孢子体和配子体的PSII活性随温度和光强的变化趋势不明显,孢子体PSII活性在温度18℃,光强为2 320 lx 时最高,配子体PSII活性在温度13℃,光强为2 800 lx时最高。孢子体PSI在酸性条件下较活跃,在pH 5.4时具有最高的PSI活性,配子体PSI在碱性条件下较活跃,PSI活性在pH 10.4时最高;孢子体PSII活性随pH的升高呈现一个先升高后降低的趋势,配子体PSII活性随pH变化趋势不明显,但都在pH 8.0处活性最高。
Knowledge about the structural and functional alterations of thylakoid membrane proteins during ontogenesis is very few due to limited, availability of pure, stable and homogenous thylakoid proteins with high activity. In this report, thylakoid membranes were isolated from the sporophyte and gametophyte cells of red alga Porphyra yezoensis. PSⅠ activity in these membrane preparations was first measured by electron transfer from ascorbate/ dichlorophenol-indophenol （ASC-DPIP） to methyl viologen （mv）; PSⅡ activity was analysed by electron transfer from H2O to 1,4-benzoquinone, with an oxygen electrode （Hansatech）. The results showed that PSⅠ from both sporophytes and gemetophytes had the highest activity at a temperature of 18℃ and light intensity of 2 320 lx, it was 579 and 406μmol/（mg, h）, respectively. No obvious changes in the PSⅡ activities within the same range of temperature and light intensity. A slightly high activity of PSⅡ from sporophytes was detected at 18 ℃ and 2 320 lx, where oxygen evolution was 499 μmol/（mg, h）, while the relatively higher activity of PSⅡ from gametophyte was 573 μmol/（mg, h）, obtained at 1S℃ and 2 800 lx. The activities of PSⅠ and PSⅡ were also measured in the pH range from 5.4 to 10.4. In comparison with gametophytes, the PSⅠ from sporophytes was more active at lower pH, with the highest activity at pH 5.4, that of gametophytes was at pH 10.4. On the other hand, the activity of PSⅡ from sporophytes was significantly higher at pH 8.0, and oxygen evolution reached 1 038 μmol/（mg, h）. However, the activity of PSⅡ from gametophytes showed no significant change in the same conditions, the activity was 394 μmol/（mg, h）. These observations imply that the composition of subunits and organization of chlorophylls might be different between PSⅠ and PSⅡ protein complexes in sporophytes and gemetophytes of Porphyra.
出处
《海洋科学》
CAS
CSCD
北大核心
2005年第9期14-18,共5页
Marine Sciences
基金
国家自然科学基金资助项目(B33023019
Max-Planck-Gesellschaft)
