A Comparison of the Properties of ATPase Associated with Wheat and Cauliflower Plasma Membranes 1
AUTOR(ES)
Pomeroy, M. Keith
RESUMO
Plasma membrane-associated ATPase obtained from cauliflower (Brassica oleraceae L.) florets isolated and assayed by several different procedures was stimulated 150 to 400% by K+. In contrast, winter wheat (Triticum aestivum L. cv. Kharkov 22 MC) shoot and root ATPase obtained by the same methods exhibited only 10 to 25% stimulation by K+. The level of K+-stimulation of the wheat enzyme was not significantly increased by purifying the crude microsomal membrane fraction using sucrose density gradients. ATPase associated with density gradient-purified cauliflower membranes was inhibited by Ca2+, high ATP concentration in the presence of low Mg2+, and by several metabolic inhibitors. In contrast, the wheat enzyme was largely unaffected by all of these treatments. The plasma membranes of intact wheat and cauliflower cells gave a positive reaction with the plasma membrane-specific, phosphotungstic acid-chromic acid stain (PACP). A high proportion of the cauliflower membrane vesicles in the putative plasma membrane-enriched fraction stained with PACP, whereas only a small proportion of the wheat membrane vesicles reacted positively with PACP. These results indicate that a plasma membrane-enriched fraction has been isolated successfully from cauliflower floret tissue, but that none of the procedures used effectively separate plasma membranes from homogenates of wheat shoots and roots.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=426391Documentos Relacionados
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