The light intensity dependence of protochlorophyllide photoconversion and its significance to the catalytic mechanism of protochlorophyllide reductase.
The light-dependent step in chlorophyll synthesis by higher plants involves hydrogen transfer from NADPH+ to the porphyrin protochlorophyllide catalysed by the photoenzyme protochlorophyllide reductase. The light intensity dependence of the process has been studied in vitro using wheat etioplast membranes. The results suggest that a single photochemical event is involved in the photoconversion. In support of this conclusion we also demonstrate that illumination of these membranes with a train of ultrashort (150 fs) flashes resulted in chlorophyll accumulation. The significance of the findings in terms of possible mechanisms for the reductase are discussed.
Griffiths
W T
WT
Department of Biochemistry, School of Medical Sciences, University of Bristol, UK.
McHugh
T
T
Blankenship
R E
RE
D002384:Catalysis; D008027:Light; D009249:NADP / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010777:Photochemistry; D011521:Protochlorophyllide / Q000378:metabolism*; D013053:Spectrophotometry; D014908:Triticum / Q000378:metabolism*
D011521:Protochlorophyllide; D009249:NADP; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase