scholarly journals Light modulation of the activity of protochlorophyllide reductase

1980 ◽  
Vol 189 (1) ◽  
pp. 125-133 ◽  
Author(s):  
R E Mapleston ◽  
W T Griffiths
Keyword(s):  
Light Modulation ◽  
Protochlorophyllide Oxidoreductase ◽  
Constant Illumination ◽  
Protochlorophyllide Reductase ◽  
Etiolated Plants

Illumination of etiolated plants effects the activity of protochlorophyllide reductase (NADPH-protochlorophyllide oxidoreductase) in the plastids. Constant illumination or a 2-min light-triggering of etiolated plants leads to an approx. 80% decrease in activity of the enzyme, a change that can be reversed by returning the plants to darkness. The change in activity results from an alteration of the Vmax. rather than Km. Despite the fact that exogenous pigments effect the activity of the enzyme in vitro, no correlation could be drawn between the concentrations of pigments in vivo and activity of the enzyme.

scholarly journals A Nodulin cDNA with Homology to Protochlorophyllide Reductase

1994 ◽  
Vol 104 (1) ◽  
pp. 289-290 ◽  
Author(s):  
R. C. Wilson ◽  
J. B. Cooper
Keyword(s):  
Protochlorophyllide Reductase

scholarly journals Cloning and sequencing of protochlorophyllide reductase

1990 ◽  
Vol 265 (3) ◽  
pp. 789-798 ◽  
Author(s):  
P M Darrah ◽  
S A Kay ◽  
G R Teakle ◽  
W T Griffiths
Keyword(s):  
Amino Acid ◽  
Chemical Analysis ◽  
Amino Acid Sequence ◽  
Cdna Library ◽  
Avena Sativa ◽  
Cdna Clones ◽  
Lambda Phage ◽  
Cloning And Sequencing ◽  
Protochlorophyllide Reductase ◽  
Cnbr Cleavage

Putative protochlorophyllide reductase cDNA clones (252 and 113) were isolated from an etiolated-oat (Avena sativa) cDNA library. These were used to indirectly characterize a further clone, p127, isolated from a lambda-phage gt11 cDNA library. The latter (1.15 kb in length) was sequenced, and the derived amino acid sequence was shown to be remarkably similar to that derived from chemical analysis of a CNBr-cleavage fragment of the purified reductase, p127 codes for more than 95% of the reductase protein.

scholarly journals Substrate-specificity studies on protochlorophyllide reductase in barley (Hordeum vulgare) etioplast membranes

1980 ◽  
Vol 186 (1) ◽  
pp. 267-278 ◽  
Author(s):  
W T Griffiths
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Hordeum Vulgare ◽  
Substrate Specificity ◽  
Acid Group ◽  
Carboxylic Acid Group ◽  
Naturally Occurring ◽  
Protochlorophyllide Reductase ◽  
Nickel Copper ◽  
Etioplast Membranes

1. The substrate specificity of the enzyme protochlorophyllide reductase in barley (Hordeum vulgare) etioplasts was investigated. 2. It was shown that naturally occurring esterified protochlorophyllide and chemically prepared protochlorophyllide methyl ester are not substrates for the enzyme, suggesting an important role for the C-7 carboxylic acid group in binding of the porphyrin to the enzyme. 3. Removal of magnesium from the protochlorophyllide leads to inactivity of the compound as a substrate for the enzyme. However, activity can be restored by replacing the magnesium with zinc, whereas nickel, copper or cobalt failed to restore substrate activity. 4. Binding of the second substrate, NADPH, to the enzyme probably occurs through the 2'-phosphate group in the coenzyme.

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