Biomaterial Database

Two possible 3-(3,4-dichlorophenyl)-1,1-dimethylurea-insensitive sites in photosystem II of spinach chloroplasts. 1980

R Barr, and F L Crane

Two possible 3-(3,4-dichlorophenyl)-1,1-dimethylurea-insensitive sites were found in PS II of spinach chloroplasts, depending on the pH of the assay medium used. The low site (pH 6) can be inhibited by certain quinolines, such as 8-hydroxyquinoline at concentrations less than 50 microM. The high pH site (pH 8) can be inhibited by disodium cyanamide, folic acid, or 5,6-benzoquinoline at concentrations from 50 microM to 5 mM. With the exception of orthophenanthroline, which stimulates the high pH site but does not show much inhibition at low pH, all other inhibitors gave opposite effects at the pH values used, i.e., they stimulated at low pH or inhibited at high pH, or vice versa. Several mechanisms for the observed effects are discussed.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008982	Molybdenum	A metallic element with the atomic symbol Mo, atomic number 42, and atomic weight 95.95. It is an essential trace element, being a component of the enzymes xanthine oxidase, aldehyde oxidase, and nitrate reductase.	Molybdenum-98,Molybdenum 98
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010788	Photosynthesis	The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)	Calvin Cycle,Calvin-Benson Cycle,Calvin-Benson-Bassham Cycle,Carbon Fixation, Photosynthetic,Reductive Pentose Phosphate Cycle,Dark Reactions of Photosynthesis,Calvin Benson Bassham Cycle,Calvin Benson Cycle,Cycle, Calvin,Cycle, Calvin-Benson,Cycle, Calvin-Benson-Bassham,Photosynthesis Dark Reaction,Photosynthesis Dark Reactions,Photosynthetic Carbon Fixation
D010944	Plants	Multicellular, eukaryotic life forms of kingdom Plantae. Plants acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations. It is a non-taxonomical term most often referring to LAND PLANTS. In broad sense it includes RHODOPHYTA and GLAUCOPHYTA along with VIRIDIPLANTAE.	Plant
D002736	Chloroplasts	Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.	Chloroplast,Etioplasts,Etioplast
D004237	Diuron	A pre-emergent herbicide.	DCMU,3-(3,4-Dichlorophenyl)-1,1-dimethylurea
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000643	Ammonium Chloride	An acidifying agent that has expectorant and diuretic effects. Also used in etching and batteries and as a flux in electroplating.	Sal Ammoniac,Ammoniac, Sal,Chloride, Ammonium
D012825	Silicon	A trace element that constitutes about 27.6% of the earth's crust in the form of SILICON DIOXIDE. It does not occur free in nature. Silicon has the atomic symbol Si, atomic number 14, and atomic weight [28.084; 28.086].	Silicon-28,Silicon 28