Intrathylakoid space

Intrathylakoid space Extra thy1 akoid space ... 

If the model proposed by Andersson and Anderson [109] of total separation of PS I and PS II in the granal chloroplasts were to be accepted, electron transport from the PS II acceptors to P-700 would require a mobile electron carrier(s) which should diffuse laterally in the membrane fast enough to account for the observed electron transport rate. Plastoquinone [112] and plastocyanin are the candidates of choice for this role. The former has been shown to be present at approximately the same activity in the partitions and in the stroma-exposed membranes [43], while PC is known to be located in the intrathylakoid space [113],... 

N-terminus of the mature polypeptide and a single hydrophobic sequence, which may be involved in anchoring Cyt/in the thylakoid membrane, is located near the C-terminus. A model of Cyt / with a single membrane-spanning a-helix and the bulk of the polypeptide in the intrathylakoid space has been proposed and tested by partial proteolytic cleavage [105],... 

Protection of thylakoids by large molecules might be explained in several ways. Perhaps the thylakoid membrane is sensitive to solute injury only on the outer side, or the intrathylakoid space contains, even after long incubation, little of the added cryotoxic solute, or penetration of the membrane by normally nonpenetrating solutes becomes possible under freezing conditions (76). 

By means of suitable membrane-active additives, we have attempted to modify the structure of isolated thylakoids and thereby increase membrane permeability. Changes in resistance of the membranes to freezing were then determined. Figure 11 shows the effect of sodium caprylate on the permeability of thylakoids to protons. In the absence of the compound, illumination causes proton transfer across the thylakoids and acidification of the intrathylakoid space. A fluorescent weak amine was used to monitor formation of the proton gradient (86). When the light was turned off, protons moved slowly back across the thylakoid membrane. Transport followed first-order kinetics. In the presence of caprylate... 

Enzymes and lipophilic secondary products found in the nonparticulate fraction probably are located in the stroma. Hydrophilic secondary products may be located in the nonplasmic compartments, e.g., the intrathylakoidal space. 

The synthesis of ATP during photosynthesis, called photophosphorylation, is presently accounted for in terms of the chemiosmotic hypothesis (Section 13.6). The proton gradient is established across the thylakoid membrane by the electron-driven translocation of protons from the stroma into the intrathylakoid space. Proton translocation may be effected at three stages during... 

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