PREPARATION AND PROPERTIES OF A MITOCHONDRIAL FRACTION FROM WHEAT STEM RUST UREDOSPORES

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Abstract
Ungerminated uredospores of Puccinia graminis f. sp. tritici Erikss. & Henn. race 15B were disrupted in a buffered sucrose serum albumin solution, using a "Teflon" pestle homogenizer and glass beads 80 μ in diameter. A particulate fraction was sedimented between 2000 and 30,000 × g and its oxidation of Krebs' cycle acids measured manometrically. Endogenous respiration of washed preparations was low or negligible. Oxygen uptake was observed with succinate (40 to 60 μl/hour mg protein), α-ketoglutarate, malate, citrate, and isocitrate (10 to 30 μl/hour mg protein) but not with fumarate or pyruvate. Succinate oxidation was sensitive to heat, cyanide, and malonate.Aspects of the extraction procedure were examined for effects on yield and activity. Serum albumin in the grinding medium, very low grinding speed, and short grinding time favored high activity per mg protein. Glass beads increased the yield with the "Teflon" pestle while an all-glass homogenizer gave preparations of low activity.Oxidatively active particle suspensions reduced Janus green B and were shown by electron microscopy to consist of vesicles and some mitochondria.