Studies in the Metabolism of Plant Cells XI. the Donnan Equilibration and the Ionic Relations of Plant Mitochondria

Abstract

Ionic relations of mitochondria from red beetroot tissue (Beta vulgaris L.) sllsponded in various salt media were studied. Under the conditions of the experiments the mitochondrial suspensions behaved us a two-phase system, one coni,aining immobile ions and showing Donnan effects. Rome differences between mitochondria which showed simple Donnan charactoristics and those accumulating chloride ions aro described.

Absorption of Iron by Enzymically Isolated Leaf Cells

“…Honda and Robertson (9) proposed Ihat the inhibitory effects of DNP on salt accumulation was an inhibition of tbe production of ATP. Their results with red beet mitochondria .suggest that oxidative phosphoryiation and ion uptake could be different manifestations of electron transport (17).…”

Studies in the Metabolism of Plant Cells XII. Ionic Effects on Oxidation of Reduced Diphosphopyridine Nucleotide and Cytochrome C by Plant Mitochondria

“…Both ATP and EDTA may complex calcium within the mitochondria (Raaflaub 1955). Isolation of beetroot mitochondria in EDTA solutions was found to decrease the content of mitochondrial calcium (Honda and Robertson 1956) and to increase both the rate of oxidations of succinate, malate, and a-ketoglutarate and the accompanying phosphorylations (Robertson and Tobin, unpublished data). Although previous experiments did not show beneficial effects of EDTA in the demonstration of salt accumulation by mitochondria (Honda and Robertson 1956) or improvement in the resolution of their fine structure (Farrant et al 1956), the modifications in preparative methods have now shown effects on mitochondrial oxidation of DPNH.…”

“…Since high yields of mitochondria were not required, modifications of previous methods (Honda and Robertson 1956) were introduced to shorten the preparative time and to decrease the centrifugal force required to sediment the mitochondria isolated from commercial red beetroot (Beta vulgaris L.).…”

“…The brei was filtered through muslin and centrifuged for 5 min at 325 g. The supernatant was decanted, filtered through muslin, and recentrifuged for 15 min at 10,000 g. The resulting supernatant was retained in order to measure its pH, which was taken as the brei pH. The sedimented particles or mitochondria corresponded to those previously used for studies on respiratory activity, active and passive behaviour in salt solutions (Robertson et al 1955;Honda and Robertson 1956), and fine structure of mitochondria (Farrant et al 1956). These mitochondria if used without further manipulations were called "unwashed" mitochondria.…”

“…The active and passive roles of mitochondria in the systems responsible for salt uptake by plant cells have been studied by Robertson et al (1955) and Honda and Robertson (1956). The influence of salts on the activity of particulate cyto.…”