Zur Problematik des In-vivo-Einsatzes von Kalium-Jodid und Natrium-Azid als spezifische Triplett-Quencher von Flavinen

Summary The effect of the flavin-quenchers KI and NaN 3 on the red light- and blue light-controlled chloro-plast movements has been investigated. The following results were obtained: 1. Blue light- as well as red light-controlled chloroplast movements are strongly inhibited by KI and by NaN 3 , respectively. 2. In all types of chloroplast movements, which have been investigated in Mougeotia (IWLM, CWLM, SLM), the inhibitory effect of KI is weakened when exogeneous ATP (or ADP) but not at all ITP (or IDP) is applied simultaneously with KI. 3. Both photosynthetic oxygen evolution and respiration in darkness get inhibited by KI and by NaN 3 , respectively. 4. KI dissolved in aqua dest. or in sorbitol (10 −4 M) almost completely loses its severe inhibitory effect on chloroplast movements. 5. If KI is dissolved in aqua dest. or in sorbitol containing CaCl 2 (10 −2 M), its strong inhibitory effect upon any light-oriented chloroplast movement is restored. If KI is dissolved together with MgCl 2 , it restrains chloroplast movement in the weak but not in the strong light. 6. Some experiments demonstrate that the receptibility of the cell for KI is increased by additionally CaCl 2 . The amount of KI penetrating the cell depends highly on qualities and quantities of light.