Separation and characterization of stroma and grana membranes — evidence for heterogeneity in antenna size of both Photosystem I and Photosystem II

The results show that the grana-derived membranes contain PS Iα and PS IIα which have larger functional antenna sizes than the corresponding PS Iβ and PS IIβ of the stroma membranes

Eva Andreasson

2003

Scholarcy highlights

  • A rapid procedure to fractionate the thylakoid membrane into two well-separated vesicle populations, one originating from the grana and the other from the stroma-membrane region, has been developed
  • The grana membranes comprise, on chlorophyll basis, about 60% of the thylakoid material and are enriched in PS II, and contain some PS I, while the stroma membranes comprise about 40% and are enriched in PS I, and contain some PS II
  • The rate of P-700 photooxidation under low light illumination was higher for PS Iα than for PS Iβ, showing that PS Iα has a larger antenna
  • The PS II of the grana fraction reached half-saturation at half the light intensity compared to the PS II of the stroma-membrane fraction
  • The results show that the grana-derived membranes contain PS Iα and PS IIα which have larger functional antenna sizes than the corresponding PS Iβ and PS IIβ of the stroma membranes
  • The results suggest that the photosystems of the grana are designed to allow effective electron transport both at low and high light intensities, while the stroma-membrane photosystems mainly work at high light intensities as a supplement to the grana systems

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