WorldCat Identities

Parham, Ramin 1962-

Overview
Works: 4 works in 10 publications in 2 languages and 67 library holdings
Genres: History  Biography 
Classifications: DS318.8, 955
Publication Timeline
Key
Publications about  Ramin Parham Publications about Ramin Parham
Publications by  Ramin Parham Publications by Ramin Parham
Most widely held works about Ramin Parham
 
Most widely held works by Ramin Parham
Histoire secrète de la révolution iranienne by Ramin Parham ( Book )
4 editions published in 2009 in French and held by 53 WorldCat member libraries worldwide
Né à Ispahan : document by Ramin Parham ( Book )
2 editions published in 2013 in French and held by 6 WorldCat member libraries worldwide
Iran : en finir avec la République islamique by Ramin Parham ( )
in French and held by 3 WorldCat member libraries worldwide
Localization, biochemical characterization, and solubilization of (4-vinyl) chlorophyllide a reductase, a novel chlorophyll a biosynthetic enzyme by Ramin Parham ( )
2 editions published in 1994 in English and held by 2 WorldCat member libraries worldwide
(4-vinyl) chlorophyllide a reductase (4VCR), catalyses the conversion of divinyl chlorophyllide a (DVChlide a) to monovinyl chlorophyllide a (MVChlide a). The latter is the immediate precursor of monovinyl chlorophyll a (MVChl a) in plants and algae. In reaction center and light harvesting pigment-protein complexes, MVChl a is the main, photosynthetically active protein. 4VCR has been localized in membrane fractions of plastids isolated from etiolated cucumber (Cucumis sativus L.) cotyledons. The enzyme has also been detected in two monocotyledonous species, namely corn (Zea mays L.), and barley (Hordeum vulgare L.). In these species, 4VCR activity has been shown to be maximal in etiolated tissues and drop sharply upon illumination. 4VCR requires the reducing power NADPH as source or hydride ion. Neither a metal ion, nor any cofactor requirement, other than NADPH, could be demonstrated for 4VCR activity. The latter has been shown to be optimal at 30$spcirc$C, pH 6.3. Michaelis-Menten constants for DVChlide a and NADPH have been determined to be respectively 0.09-2.00 $mu$M, and 1.1 mM. 4VCR's low Km value for DVChlide a, in parallel with substrate specificity studies suggested that the enzyme is highly specific for DVChlide a and not other, early and late, divinyl intermediates. The narrow substrate specificity of this bridge-enzyme contrasts with the broad specificity of the forward enzymes of the pathway. The diphenyl ether herbicide acifluorfen methyl (AFM), and the photodynamic herbicide modulator 1, 10-phenanthroline (OPh), inhibited 4VCR activity with respective Ki values of 0.86 and 1.47 mM. The structural requirements of this inhibition have been demonstrated to lie on the presence of at least one nitrogen in a 3-ring, heterocyclic, phenanthroline-related inhibitor. Moreover, electrostatic interactions involving the fractional charge at position 7 of the inhibitor heterocycle appear to be at play in the binding of the inhibitor to the enzyme. Preliminary structural studies of the enzyme have revealed the presence of free, and accessible cystein residues, essential for enzyme activity. Finally, strong inhibition caused by the flavine antagonist quinacrine, suggested that a flavine nucleotide may be involved in the transfer of the hydride from NADPH to DVChlide a
 
Audience Level
0
Audience Level
1
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Audience level: 0.80 (from 0.00 for Iran : en ... to 1.00 for Localizati ...)
Languages
French (8)
English (2)