Identification of Chl-binding proteins in a PS II preparation from spinach

Abstract

Using a mild solubilization procedure we have been able to detect several Chl-binding proteins by SDS-urea-PAGE. Their molecular masses were 46, 42, 34, 32, 29-24 and approx. 110 kDa (presumably a CPI contamination). The stability of the Chl-protein complexes depended strongly on experimental conditions. A very faint band at 34-30 kDa was resolved in visible light (in 40–50% of the experiments). With a more sensitive fluorometric technique (illumination at 366 nm, fluorescence detection in the red) we identified two Chlcontaining bands in the 30 kDa region. Limited proteolysis studies with trypsin revealed that the extent of the enzymatic degradation of some Chl-binding proteins in vitro is obviously dependent on pH and the presence of Ca 2+.