A study on the energy-dependent quenching of chlorophyll fluorescence by means of photoacoustic measurements

Abstract

The mechanism of energy-dependent quenching (qE) of chlorophyll fluorescence was studied employing photoacoustic measurements of oxygen evolution and heat release. It is shown that concomitant to the formation of qE the yield of open reaction centers φp decreases indicating that qE quenching originates from a process being competitive to fluorescence as well as to photochemistry. The analysis of heat release (rate of thermal deactivation) shows: 1. The competitive process is not given by a still unknown energy storing process. 2. If the competitive process would be a futile cycle the life-times of the involved intermediates had to be faster than 50 μs.The results of the photoacoustic measurements are in line with the idea that qE quenching originates from an increased probability of thermal deactivation of excited chlorophylls.

Study of photosystem 2 heterogeneity in the sulfur-deficient green alga Chlamydomonas reinhardtii

“…The quenching of Chl fluorescence during several seconds after the P peak is due to a high-energy non-photochemical quenching, related to the formation of the DpH thylakoid gradient (Dau and Hansen 1990). The JIP test parameter q E introduced as characteristic of DpH-dependent fluorescence quenching (see Table 1) declined abruptly by about 70% during 12 h period of C. reinhardtii SD and remained practically invariable upon longer incubation (Table 3), reflecting the retardation of the light-induced quenching mechanism.…”

The manganese complex of photosystem II in its reaction cycle—Basic framework and possible realization at the atomic level

“…The above and other spectroscopic techniques (see Section 2.3 and, e.g. [64][65][66][67][68][69][70][71][72][73][74][75]) also may provide insight into the reaction dynamics, i.e. the structural changes associated with advancement in the reaction cycle.…”

The Use and Characteristics of the Photoacoustic Method in the Study of Photosynthesis

“…::; 1.02), <pFml ::; 0.021. In another study (38), which used intense modulated light, and hence had an improved signal/noise ratio, R21R! "" 1.05 and qN '" 0.6, from which <PFm!…”