Action of Heavy Metals on Hill Activity and O₂ Evolution in Anacystis nidulans

Abstract

Addition of 5 micromolar Cu2+, Cd2+, and Zn2+ was inhibitory to 10 micromolar H202-supported Hill activity (dichlorophenolindophenol reduction) and 02 evolution in membrane preparation from Anacystis nidulans.

Toxic Effects of Copper on Photosystem II of Spinach Chloroplasts

“…They found that the activity of H20 -* DCIP was inhibited by copper, and artificial donors such as DPC failed to restore it, suggesting an inhibition close to the reaction center of PSII. However, our observation is different from that of Singh and Singh (17), who have studied the effect of copper on the Hill activity in Anacystis nidulans and have suggested a site of copper action at the level of Cyt f.…”

“…Shioi et al (15) suggested that it was due to the direct interaction of copper with ferredoxin on the reducing side of PSI. Studies on PSII showed that the Hill reaction was also sensitive to copper (4,(15)(16)(17). Some reports indicated that the inhibited DCIP2 photoreduction rate could not be restored by adding artificial donors like DPC (4,16), suggesting that the inhibition was between the electron donating site of DPC and the PSII reaction center.…”

“…Some reports indicated that the inhibited DCIP2 photoreduction rate could not be restored by adding artificial donors like DPC (4,16), suggesting that the inhibition was between the electron donating site of DPC and the PSII reaction center. However, a recent study by Singh and Singh (17) on the iaction of heavy metals on the Hill activity suggested that copper inhibition was located beyond the DCMUsensitive site and at the level of Cyt.…”

Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b559in a Chlamydomonas reinhardtii PSI Minus Mutant

“…Simultaneously, the irreversible Cu(II) induced inactivation of the acceptor side has been observed [12]. The primary quinone acceptor Q A [12], the pheophytin(Pheo)-Q A -Fe region [13], the non-heme iron [14,15] and a secondary quinone acceptor Q B [16] have been identified as targets of Cu 2+ action. Copper ions have also been found to influence redox properties of cytochrome b 559 , one of the most intriguing components of PSII.…”

O2‐induced inactivation of nitrogenase as a mechanism for the toxic action of Cd2+ on Nostoc UAM 208

“…It cannot, however be excluded that cadmium is also foxic in other ways. Like other heavy metals, Cd^* has been suggested to interact negatively with ATP production, reductant pools, and photosynthetic electron transport (Singh & Yadava, 1983Singh & Singh, 1987;Husaini & Rai, 1991), and to cause structural changes: a general reduction in cell dimension, thylakoid surface area, and number and volume of inclusion bodies and wall layers (Rachlin, Jensen & Warkentine, 1984;Rai, Jensen & Rachlin, 1990). There may be a number of different mechanisms for cell damage by Cd^^ that could act independently or together to inhibit different metabolic processes, including Ng fixation, and finally growth.…”