ABSTRACT
Simultaneous measurements of fluorescence and thermal emission have been made by a combined fluorescence and photoacoustic techniques on isolated thylakoids pretreated by a prolonged illumination of saturating light. The traces of the signals are used to calculate four characteristic parameters, energy storage, half-saturation intensity, number of photons to close reaction center, and a constant for quasi-equlibria between (re)oxidized and reduced quinone acceptors. These parameters are used to study the response of photosynthetic apparatus functioning under photoinhibition stress. The defense mechanism seems to possess an efficient cooperativity of reaction centers under stress conditions.
Subject(s)
Benzoquinones/chemistry , Hot Temperature , Light , Light-Harvesting Protein Complexes , Photons , Plant Physiological Phenomena , Spinacia oleracea/metabolism , Temperature , Thylakoids/chemistry , Time FactorsABSTRACT
The molecular complexes of sulfanilamide, sulfaguanidine, sulfapyridine, sulfadiazine, sulfamerazine, sulfadimidine and sulfathizole with chloranil and dichlorodicyano-p-benzoqunone have been prepared and investigated by IR, electronic absorption and proton magnetic resonance spectroscopy. Primary interaction between the different donors and acceptors is through pi-pi* electron transfer from the HOMO on the donor to the LUMO on the acceptor. In addition, pi-pi* and/or hydrogen bonding can be operative within the molecular complexes