[Comparative study of inhibiting photophosphorylation and light-activated ATP hydrolysis in pea chloroplasts by N,N'-dicyclohexylcarbodiimide].
Inhibition kinetics of photophosporylation in chloroplast preparations preincubated by N,N'-dicyclohexylcarbodiimide (DCCD) in darkness has been studied. It was found that the higher membrane concentration the lower DCCD/chlorophyll relation sufficient for blocking of ATP synthesis and light-activated hydrolysis. Comparative studies of DCCD-inhibition of the ATP synthesis and light-activated hydrolysis showed that the latter process was more sensitive to DCCD. In the thylakoid suspensions with concentration Chlorophyll 4 mg/ml 50% inhibition of ATP hydrolysis was observed at the DCCD/Chlorophyll ratio of 0.012, and 50% inhibition of ATP--at 0.02. Inhibition kinetics of light-activated hydrolysis and synthesis corresponded to Hill equation with Hill coefficients 9.1 and 5.8 correspondingly. Different mechanisms of participation of DCCD-binding subunits in ATP-synthesis and ATP-hydrolysis processes have been discussed.
Zolotareva
E K
EK
Kholodny Botany Institute, NAS of Ukraine, Kyiv. postmaster@ligazap.kiev.ua
Dovbysh
E F
EF
Onoĭko
E B
EB
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002736:Chloroplasts / Q000187:drug effects* / Q000378:metabolism; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology*; D006868:Hydrolysis; D007700:Kinetics; D008027:Light; D018532:Pisum sativum / Q000378:metabolism*; D010766:Phosphorylation
D004024:Dicyclohexylcarbodiimide; D000255:Adenosine Triphosphate