Isolation and characterization of photoactive complexes of NADPH:protochlorophyllide oxidoreductase from wheat |
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Authors: | Mohammed Aziz Ouazzani Chahdi Benoît Schoefs Fabrice Franck |
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Institution: | (1) Laboratory of Photobiology, Institute of Plant Biology B22, University of Liège B-4000 Liège/Sart-Tilman, Belgium, BE |
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Abstract: | A photoactive substrate-enzyme complex of the NADPH:protochlorophyllide oxidoreductase (POR; EC 1. 3. 1. 33) was purified
from etiolated Triticum aestivum L. by gel chromatography after solubilization of prolamellar bodies by dodecyl-maltoside. Irradiation by a 1-ms flash induced
the phototransformation of protocholorophyllide a (Pchlide) with −196 °C absorbance and emission maxima at 640 and 643 nm, respectively. The apparent molecular weight of this
complex was 112 ± 24 kDa, which indicates aggregation of enzyme subunits. By lowering the detergent concentration in the elution
buffer, a 1080 ± 250-kDa particle was obtained which displayed the spectral properties of the predominant form of photoactive
Pchlide in vivo (−196 °C absorbance and fluorescence maxima at 650 and 653 nm). In this complex, POR was the dominant polypeptide.
Gel chromatography in the same conditions of an irradiated sample of solubilized prolamellar bodies indicated rapid disaggregation
of the complex after Pchlide phototransformation. High performance liquid chromatographic analysis of the POR complexes obtained
using two detergent concentrations indicates a possible association of zeaxanthin and violaxanthin with the photoactive complex.
Received: 25 February 1998 / Accepted: 8 June 1998 |
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Keywords: | : Carotenoid Etioplast NADPH:proto chlorophyllide oxidoreductase Protochlorophyllide Triticum |
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