TY  - JOUR
A1  - Vierke, Gerhard
T1  - The effect on ammonium chloride on the kinetics of the back reaction of photosystem II in Chlorella fusca and in chloroplasts in the presence of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea
T2  - Zeitschrift für Naturforschung, C
N2  - The effect of NH4Cl on the kinetics of the back reaction of photosystem II as derived from luminescence measurements was investigated in dark adapted Chlorella in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) at different temperatures. The kinetics of the back reaction which, under these conditions, leads to the reduction of the S2 state by the primary electron acceptor Q- of photosystem II was observed to be considerably slowed down in the presence of NH4Cl.
Analysis of the kinetic results in the light of the theory of the back reaction developed by Mar and Roy (J. Theor. Biol. 48, 257-281 (1974)) revealed two opposite effects of NH4Cl to be present simultaneously:
1) The enthalpy of activation of the back reaction was lowered (catalyzing effect of NH4Cl)
2) The frequenca factor which indicates the number of collisions of the reacting molecules in the membrane per second is largely decreased (inhibitory effect of NH4Cl).
This reduction of the mobility of the recombining species of the back reaction is the predominant effect of NH4Cl. It is suggested that this effect is due to a change of the conformational state of the membrane induced by dissolution of relative large amounts of NH? within the lipid phase of the thylakoid membrane. This hypothesis is supported by the observation that the value of the exciton yield of the back reaction changes upon addition of NH4Cl.
 Photosystem II
KW  - Kinetics of the Back Reaction
KW  - Photosystem II
KW  - Ammonium Chloride
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/71395
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-713959
SN  - 0939-5075
SN  - 1865-7125
VL  - 35.1980
IS  - 5-6
SP  - 451
EP  - 460
PB  - Verlag der Zeitschrift für Naturforschung
CY  - Tübingen
ER  -