Homogenates ofDunaliella primolecta, D. salinaandD. tertiolectawere assayed for glycollate oxidase and glycollate dehydrogenase. BothD. primolectaandD. salinabut notD. tertiolectashowed substantial glycollate-dependent O2-uptake which is characteristic of glycollate oxidase.L-Lactate was an alternative substrate and both glycollate- andL-lactate-dependent O2uptake were insensitive to 2 mM cyanide. Glycollate dehydrogenase, measured by following the glycollate-dependent reduction of 2,6-dichlorophenolindophenol under aerobic conditions, was present inD. primolecta, D. salinaandD. tertiolecta. In the presence of glycollate andD-lactate, rates were additive so both glycollate andD-lactate dehydrogenases are present in the homogenates. Glycollate andD-lactate oxidation were both inhibited by 2 mM cyanide. Organelles released from phototrophically grown cells ofD. primolectawere separated by isopycnic centrifugation on sucrose gradients. Glycollate oxidase was present in the peroxisome fraction at an equilibrium density of 1.25 g/cm3, while the major peak of glycollate dehydrogenase activity was in the mitochondrial fraction at an equilibirium density of 1.22 g/cm3.
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