Ionic and pH transitions triggering chloroplast post-illumination luminescence

• Published in: Archives of biochemistry and biophysics Vol. 129; no. 2; pp. 711 - 719
• Main Authors: Miles, C.D., Jagendorf, A.T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.1969
• Subjects: Adenosine Triphosphate - biosynthesis; Adenosine Triphosphate - metabolism; Chlorides - pharmacology; Chloroplasts - metabolism; Darkness; Electrolytes; Hydrogen-Ion Concentration; Light; Luminescent Measurements; Plants, Edible - metabolism; Time Factors
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/0003-9861(69)90232-X

The postillumination “chemiluminescence” of isolated spinach chloroplasts, previously shown to be caused by an acid-base transition, is found to be caused also by a transition from a low to a high ionic strength environment. The salt induction of luminescence is in competition with the acid-base luminescence; whichever comes first prevents light emission upon going through the second process. It was discovered that suddenly lowering the pH to 3.2 or below also causes light emission. The acid procedure induces up to eight times as much light emission as the others, and does not seem to compete with them in that raising the pH or the salt concentration causes a further amount of luminescence even after the acid-induced burst. All three procedures share a sensitivity to phosphorylation inhibitors and to DCMU, and all require preillumination of the chloroplasts. Chloroplasts subject to a low to high salt transition do not go into a high energy state, as judged by either ATP formation or ATPase activation. Evidence is presented suggesting that even in the case of acid-base transition the high energy state is not the trigger for light emission.