Characterization of ATPase activity associated with corn leaf plasma membranes |
| |
Authors: | Perlin D S Spanswick R M |
| |
Institution: | Section of Plant Biology, Division of Biological Sciences, Plant Science Building, Cornell University, Ithaca, New York 14853. |
| |
Abstract: | 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. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|