Action of heavy metals on hill activity and O/sub 2/ evolution in Anacystis nidulans
Addition of 5 micromolar Cu/sup 2 +/, Cd/sup 2 +/, and Zn/sup 2 +/ was inhibitory to 10 micromolar H/sub 2/O/sub 2/-supported Hill activity (dichlorophenolindophenol reduction) and O/sub 2/ evolution in membrane preparation from Anacystis nidulans. The reversal of Cd/sup 2 +/ and Zn/sup 2 +/ inhibition, in contrast to Cu/sup 2 +/, by exogenously added catalase suggested that the former cations were inhibitory to H/sub 2/O/sub 2/ degradation. Ascorbic acid (20 micromolar) supported 27% of the Hill activity which was insensitive to DCMU (10 micromolar) and the remaining activity, attributable to the DCMU sensitive process, was sensitive to inhibition by Cu/sup 2 +/ only. It is suggestive that the action site of Cd/sup 2 +/ and Zn/sup 2 +/ is located between the electron donation sites of H/sub 2/O/sub 2/ and ascorbic acid, while that of Cu/sup 2 +/ is located beyond it. Electron donation by reduced glutathione was insensitive to DCMU and Cu/sup 2 +/, indicating that the action site of Cu/sup 2 +/ is prior to its electron donation site. Further, the phenanthroline (10 micromolar) reversal of Cu/sup 2 +/ inhibition of Hill activity suggested a tentative action site of Cu/sup 2 +/ at the level of cytochrome.
- Research Organization:
- Banaras Hindu Univ., Varanasi, India
- OSTI ID:
- 6609676
- Journal Information:
- Plant Physiol.; (United States), Vol. 83:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CADMIUM COMPOUNDS
TOXICITY
COPPER COMPOUNDS
CYANOBACTERIA
SENSITIVITY
ZINC COMPOUNDS
CATIONS
HYDROGEN PEROXIDE
INHIBITION
OXYGEN
CHARGED PARTICLES
ELEMENTS
HYDROGEN COMPOUNDS
IONS
MICROORGANISMS
NONMETALS
OXYGEN COMPOUNDS
PEROXIDES
TRANSITION ELEMENT COMPOUNDS
560300* - Chemicals Metabolism & Toxicology