Atractyloside Inhibition of Adenine Nucleotide Translocation in Mitochondria from Hypocotyls of Vigna sinensis cv. Seridó |
| |
Authors: | M SILVA LIMA N D DENSLOW D FERNANDES de MELO |
| |
Institution: | Department of Biochemistry and Molecular Biology, University of CearáCaixa Postal, 1065 —60.000 Fortaleza, Ceará, Brazil |
| |
Abstract: | The translocation of adenine nucleotides into mitochondria isolated from hypocotyls of Vigna sinensis (L.) Savi cv. Serido was examined as a function of oxidative phosphorylation. Mitochondria membrane integrity was assessed by respiratory control and ADP:O ratios. A kinetic analysis of the translocation of adenosine diphosphate into the mitochondria revealed that the mechanism of translocation obeys classical Michaclis-Menten kinetics with a Km of 25 μM for adenosine diphosphate. At moderate ratios of atraetyloside to adenosine diphosphate (lower than 0.03), atractyloside appears to be a competitive inhibitor of the translocation process, with a Ki of 0.4 μM. However, non-linear kinetic parameters are observed with ratios higher than 0.06. A concentration of 2.5 μM atractyloside is sufficient to reduce the translocation of 100 μm ADP by 50%. This represents a higher level of sensitivity to atractyloside than reported for other plants. |
| |
Keywords: | |
|
|