Electron transport pathways in spinach chloroplasts. Reduction of the primary acceptor of photosystem II by reduced nicotinamide adenine dinucleotide phosphate in the dark

Journal Article · Mon Jan 01 00:00:00 EST 1979 · Biochim. Biophys. Acta; (United States)

DOI:https://doi.org/10.1016/0005-2728(79)90101-4· OSTI ID:5063502

Mills, J D; Crowther, D; Slovacek, R E; Hind, G; McCarty, R E

Addition of NADPH to osmotically lysed spinach chloroplasts results in a reduction of the primary acceptor (Q) of Photosystem II. This reduction of Q reaches a maximum of 50% in chloroplasts maintained under weak illumination and requires added ferredoxin and Mg/sup 2 +/. The reaction is inhibited by (i) an antibody to ferredoxin-NADP/sup +/ reductase (EC 1.6.7.1), (ii) treatment of chloroplasts with N-ethylmaleimide in the presence of NADPH, (iii) disulfodisalicylidenepropanediamine, (iv) antimycin, and (v) acceptors of non-cyclic electron transport. Uncouplers of phosphorylation do not affect NADPH-driven reduction of Q. It is proposed that electron flow from NADPH to Q may occur in the dark by a pathway utilising portions of the normal cyclic and non-cyclic electron carrier sequences. The possible in vivo role for such a pathway in redox poising of cyclic electron transport and hence in controlling the ATP/NADPH supply ratio is discussed.

• Research Organization: Brookhaven Natl. Lab., Upton, NY
• OSTI ID: 5063502
• Journal Information: Biochim. Biophys. Acta; (United States), Vol. 547
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CHLOROPLASTS
ELECTRON TRANSFER
BIOLOGICAL PATHWAYS
CYTOCHROMES
EXPERIMENTAL DATA
FERREDOXIN
FLUORESCENCE
INHIBITION
MAGNESIUM
NADP
NEM
OXIDOREDUCTASES
PHOSPHORYLATION
PHOTOCHEMICAL REACTIONS
REDOX REACTIONS
SPINACH
ALKALINE EARTH METALS
CELL CONSTITUENTS
CHEMICAL REACTIONS
COENZYMES
DATA
DRUGS
ELEMENTS
ENZYMES
FOOD
IMIDES
INFORMATION
LUMINESCENCE
METALS
NUCLEOTIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
RADIOSENSITIZERS
RESPONSE MODIFYING FACTORS
VEGETABLES
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)