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KMID : 0380219940270040290
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Journal of Biochemistry and Molecular Biology
1994 Volume.27 No. 4 p.290 ~ p.296
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Characterization of Plasma Mumbrane H+-ATPase from Sunflower Hypocotyls
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Abstract
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Abstract:
@EN Plasma membrane(PM) H+-ATPase of sunflower (Helianghus annuus L.,)hypocotyls with plasma membrane vesicles prepared by aqueous two-phase partitioning was characterized. Microsomal fraction proteins were patitioned into lower and upper phases
using a
polymer concentration of 6.4%. The ATPase activity was dependent on Mg2+, but was slightly influenced by k. Molybdate, azide, and nitrate., which inhibit unspecific phosphatase, mitochondrial ATPase, and tonoplast ATPase, respectively, had little
effect
on the enzyme, reflecting the purityof the plasma membrane. However. 100 μM vanadate inhibited enzyme activity by more than 90%. Ca2+ also increasingly inhibited enzyme activity with increasing concentration, and the inhibitiory effect was
considerable
below pH7. The ATPase had a Km value of 0.38 mM ATP, an optimum pH of 6.5, and an optimum temperature of 40℃. Optimum removal of enzyme latency occurred with 0.01% Triton X-100 or 0.0025% lysolecithin, but Triton X-100 above 0.01% was
inhibitory.
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