Characterization of ATPase Activity Associated with Corn Leaf Plasma Membranes 1
AUTOR(ES)
Perlin, David S.
RESUMO
A Mg2+-dependent, cation-stimulated ATPase was associated with plasma membranes isolated from corn leaf mesophyll protoplasts. Potassium was the preferred monovalent cation for stimulating the ATPase above the Mg2+-activated level. The enzyme was substrate-specific for ATP, was inhibited by N,N′-dicyclohexylcarbodiimide, diethylstilbestrol, p-chloromercuribenzoate, and orthovanadate, but was insensitive to oligomycin or sodium azide. A Km of 0.28 millimolar Mg2+-ATP was determined for the K+-ATPase, and the principal effect of potassium was on the Vmax for ATP hydrolysis. Since potassium stimulation was not saturated at high concentrations, a nonspecific role was proposed for potassium stimulation. A nonspecific phosphatase was also found to be associated with corn leaf plasma membranes. However, it could not be determined positively whether this activity represented a separate enzyme.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=425932Documentos Relacionados
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