Plastocyanin stimulation of whole chain and photosystem I electron transport in inside-out thylakoid vesicles

Journal Article · Sun Dec 01 04:00:00 EST 1985 · Arch. Biochem. Biophys.; (United States)

DOI:https://doi.org/10.1016/0003-9861(85)90544-2· OSTI ID:5988611

Atta-Asafo-Adjei, E; Dilley, R A

Inside-out and right-side-out thylakoid vesicles were isolated from spinach chloroplasts by aqueous-polymer two-phase (dextran/polyethylene glycol) partitioning. Externally added plastocyanin stimulated the whole-chain and PSI electron transport rates in the inside-out thylakoid vesicles by about 500 and 350%, respectively, compared to about 50% stimulation for both assays in the fraction enriched in right-side-out vesicles. No apparent stimulation by plastocyanin was observed in unbroken Class II thylakoids. The electron transport between PSII and PSI in inside-out thylakoid vesicles appears to be interrupted due to plastocyanin release from the thylakoids by the Yeda press treatment, but it was restored by externally added plastocyanin. The P700 content of the inside-out membrane preparations, measured by chemical and photochemical methods, was 1 P700 per 1100 to 1500 chlorophylls while it was about 1 P700 per 500 chlorophylls for the right-side-out vesicles. The data presented support the concept of lateral heterogeneity of PS I and II in thylakoid membranes, but does not support a virtual or total absence of PSI in the appressed grana partitions. Further, the heterogeneity does not appear to be as extreme as suggested earlier. Although PSI is somewhat depleted in the appressed grana membrane region, there is adequate photochemically active P700, when sufficient plastocyanin is available, to effectively couple PSI electron transfer with the preponderant PSII in linear electron transport.

• Research Organization: Purdue Univ., West Lafayette, IN
• OSTI ID: 5988611
• Journal Information: Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 2; ISSN ABBIA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
BARYONS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHEMISTRY
CHLOROPHYLL
CHLOROPLASTS
ELECTRON TRANSFER
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
PROTONS
STIMULATION
SYNTHESIS