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|Type:||Artigo de periódico|
|Title:||Characteristics Of Ca2+ Transport By Corn Mitochondria|
|Abstract:||Mitochondria isolated from corn (Zea mays L.) coleoptiles by an improved procedure which yields functionally intact preparations are much more active in respiration-coupled Ca2+ accumulation than those employed in most earlier studies. Ca2+ uptake by these mitochondria is phosphate-dependent and is accompanied by decrease in Δψ, H+ extrusion and increase in the rate of respiration. A sigmoidal plot with a Hill coefficient of 2.22 was obtained when the rates of Ca2+ uptake were plotted as a function of free Ca2+ concentration. The K0.5 for Ca2+ influx was about 31 μM and a Vmax of 140 nmol Ca2+ per min per mg was attained at a free-Ca2+ concentration of about 120 μM. Ca2+ uptake is sensitive to inhibition by ruthenium red and Mg2+. The external free-Ca2+ concentration maintained at steady state was about 2 μM and was independent of the respiratory substrate and of external Na+, but was increased by exogenous Mg2+. In addition, this preparation of corn mitochondria has shown a much higher ability for Ca2+ retention in the presence of phosphate and NAD(P)H oxidants than liver mitochondria. © 1986.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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