title: Characterization of the photosystem II centers inactive in plastoquinone reduction by fluorescence induction.
abstract: In order to characterize the photosystem II (PS II) centers which are inactive in plastoquinone reduction, the initial variable fluorescence rise from the non-variable fluorescence level Fo to an intermediate plateau level Fi has been studied. We find that the initial fluorescence rise is a monophasic exponential function of time. Its rate constant is similar to the initial rate of the fastest phase (α-phase) of the fluorescence induction curve from DCMU-poisoned chloroplasts. In addition, the initial fluorescence rise and the α-phase have the following common properties: their rate constants vary linearly with excitation light intensity and their fluorescence yields are lowered by removal of Mg(++) from the suspension medium. We suggest that the inactive PS II centers, which give rise to the fluorescence rise from Fo to Fi, belong to the α-type PS II centers. However, since these inactive centers do not display sigmoidicity in fluorescence, they thus do not allow energy transfer between PS II units like PS IIα.
authors.affiliation: Institute of Life Science, National Tsing Hua University, 30043, Hsin-Chu, Taiwan, Republic of China.
authors.forename: B D
authors.initials: BD
authors.lastname: Hsu
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee