Alkylguanidines as Inhibitors of K+ Transport in Isolated Barley Roots
AUTOR(ES)
Lepe, Beatriz Gómez
RESUMO
It has been shown that plants can accumulate K+ through an energy-dependent process. The effect of alkylguanidines, in particular octylguanidine on the uptake of 86Rb+ by excised barley roots (Hordeum vulgare var. Apizaco LV-72), has been studied. 86Rb+ was used as tracer of K+. The uptake of 86Rb+ which is linear with time and shows saturation kinetics is inhibited by octylguanidine. Half-maximal inhibition of 86Rb+ uptake is attained at 50 μM octylguanidine. Octylguanidine induces a decrease in the Vmax of the process and increases the Km of the system for Rb+. When the effects of various alkylguanidines were studied, the following order of effectiveness was encountered; octylguanidine = hexilguanidine > butylguanidine > ethylguanidine > guanidine. This suggests that guanidines inhibit Rb+ uptake by interacting through its positively charged guanidinium group with a Rb+ carrier while the alkyl chain interacts with the hydrophobic milieu of the membrane.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541849Documentos Relacionados
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