叶绿体ATP合成酶ε亚基对菠菜叶绿体毫秒延迟发光的影响

Effect of ε Subunit of Chloroplast ATP Synthase on the Fast Phase of Millisecond Delayed Fluorescence in Spinach Chloroplast

在1℃低温条件下，经叶绿体ATP合成酶ε亚基处理的菠菜叶绿体毫秒延迟发光的快相显著高于对照，增加的快相不仅是由膜两侧的电位差所引起的，并且为光系统Ⅱ水氧化释放的质子所促进。当温度升至25℃时，ε亚基对叶绿体毫秒延迟发光快相的影响几乎消失。牛血清白蛋白处理对此快相也有轻微的增强效应。

By studying the effect of εsubunit treatment on the fast phase of millisecond delayed fluorescence inchloroplast, the relationship between protons released from water oxidation ofPS Ⅱ and coupling factor was studied.The ε subunit of coupling factor increased the fast phase of millisecond delayed fluorescence (ms-DLE ) at lowtemperature. The increased part of msDLE could be used for the synthesis ofATP in photophosphorylation (Fig. 1 ).The membrane electric potentials and theprotons released from water oxidationcontributed to the increased fast phase ofms-DLE in the presence of ε subunit (Fig. 2). It is possible that the ε subunit changed the dynamic structure of thylakoid membrane near PS Ⅱ at low temperature. To test this possibility, the effects of ε subunit on the fast phase ofmillisecond delayed fluorescence at different temperatures were compared At1℃, the increment of the fast phase ofms-DLE was apparent, while at 25℃,the increase of the fast phase of ms-DLEcause by the ε subunit is hard to be measured (Fig. 3). It is suggested that localized protons in thylakoids couldchange into delocalized protons in bulkphase with the increase of temperature .Furthermore, the ε subunit seems acting on the thylakoid membrane near PS Ⅱ tochange its dynamic structure at low temperature (Fig. 4 ), therefore, localizedprotons domain is likely to be formed .