title: Immunological studies of the binding protein for chloroplast ferredoxin-NADP+ reductase.
abstract: Monospecific rabbit antibodies against the ferredoxin-NADP+ reductase binding protein of spinach thylakoids were obtained and characterized. The immunoglobulin G (IgG) fraction gave single precipitation arcs with the purified antigen or with Triton X-100 extracts of thylakoids or the reductase binding protein complex. Antibodies against the flavoprotein behave similarly. Both antibodies agglutinated thylakoids and precipitated the diaphorase activity of a Triton X-100 extract of these membranes. Isolated Fab fragments of the IgG anti-binding protein inhibited NADP+ photoreduction in a time- and Fab concentration-dependent manner. The presence of ferredoxin diminished the rate of inhibition. In the light, the inactivation rate was higher than in dark and this effect was abolished in the presence of uncouplers. These results suggest that the binding protein is protruding from the thylakoids and could be sensing the proton gradient.
mesh_terms: D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D060365:Chloroplast Proteins; D002736:Chloroplasts / Q000502:physiology* / Q000648:ultrastructure; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D004579:Electron Transport; D005287:Ferredoxin-NADP Reductase / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D005288:Ferredoxins / Q000378:metabolism; D007140:Immunoglobulin Fab Fragments; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D008027:Light; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism* / Q000502:physiology*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010940:Plant Proteins; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D060365:Chloroplast Proteins; D005288:Ferredoxins; D007140:Immunoglobulin Fab Fragments; D008565:Membrane Proteins; D010940:Plant Proteins; D014475:Uncoupling Agents; D009249:NADP; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases; D008058:Dihydrolipoamide Dehydrogenase