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Properties of a plasmalemma atpase of the maize scutellum

, : Properties of a plasmalemma atpase of the maize scutellum. Phytochemistry (Oxford) 18(4): 555-560

Properties of a plasmalemma phosphatase of the maize [Zea mays] scutellum, tentatively identified as an ATPase were investigated. Fresh and frozen-thawed scutellum slices that had been treated with 10 mM HCl to destroy acid phosphatases were used as a source of enzyme. With the exceptions of the Na+, K+ and dinitrophenol experiments, the 2 kinds of slices gave similar results. ATP and CTP were the best substrates for the enzyme followed by TTP, UTP, CDP, ADP and GTP, UDP, nucleoside monophosphates, sugar phosphates, PPi and p-nitrophenyl phosphate were relatively ineffective as substrates. The Km for ATP and ADP were 0.65 and 5 mM, respectively, but the 2 substrates gave the same Vmax (49.8 .mu.mol Pi/h per g slices). Previously it was shown that the products of ATP hydrolysis are ADP, AMP and Pi. Using these previous results and from the time courses of ATP disappearance from the bathing solution and the appearance of Pi and ADP, it was concluded that ATP and ADP were hydrolyzed by the same enzyme. The ATPase was not inhibited by oligomycin. N-N'-Dicyclohexylcarbodiimide (DCCD) was a poor inhibitor and a water soluble analog of DCCD, 1-ethyl-3-(3 dimethylaminopropyl)-carbodiimide, gave only 33% inhibition. The relative effectiveness of divalent cations for stimulating ATPase activity was Mn2+ > Mg2+ .gtoreq. Ca2+ > Co2+. Na+ and K+ gave a small additional stimulation in the presence of Mg2+. Na+ and K+ gave a much greater stimulation when no divalent cation was added; this occurred only when fresh slices were used. Dinitrophenol also increased ATPase activity only when fresh slices were used. Both the uptake of Na+ and K+ and the action of dinitrophenol would probably lower the electrochemical gradient of protons across the plasmalemma. The different results obtained with fresh slices indicate that the ATPase in these slices was under the constraint of proton gradient.


DOI: 10.1016/s0031-9422(00)84259-4

Other references

Komyo, Etsuko, 1954: Japanese Psychodidae, II Nine new species of moth flies. Pericoma shikokuensis, P. yanoi, P. sasakawai, P. omogoensis, Trichopsychoda shogakii, T. lepida, Brunettia spinistoma, B. ishiharai, and Sycorax nipponicus.

Gu, Y., 1981: The significance of "Saber-sheath" trachea in diagnosis of cor pulmonale. Zhonghua Jie He He Hu Xi Xi Ji Bing Za Zhi 4(3): 149-150

Jones, E.S.; Vinh, A.; McCarthy, C.A.; Gaspari, T.A.; Widdop, R.E., 2008: AT2 receptors: functional relevance in cardiovascular disease. The renin angiotensin system (RAS) is intricately involved in normal cardiovascular homeostasis. Excessive stimulation by the octapeptide angiotensin II contributes to a range of cardiovascular pathologies and diseases via angiotensin type 1 recep...

Ikeda, M.; Tanifuji, N.; Yamaguchi, H.; Irie, M.; Matsuda, K., 2007: Photoswitching of conductance of diarylethene-Au nanoparticle network. A network composed of gold nanoparticles covered with diarylethene dithiophenols was prepared on an interdigitated nanogapped gold electrode to show the reversible photoswitching of the conductance due to the photochromism of the diarylethene mole...

Guo, H-lin.; Du, Z-dong., 2007: Application of coronary CT angiography and MR angiography in Kawasaki disease. Zhonghua Er Ke Za Zhi 45(6): 474-476

Cole, D.; Robb D|ROBB.D., 1974: Douglas Robb. Medical Journal of Australia 2(9): 337-338

Stankovic, N.K.rdic, B.P.ndurovic, M.T.ifunovic, D.V.lter, D., 1977: Comparative study of complete feed mixtures (prestarters) for suckling piglets. Krmiva 19 (12) 287-288

Chan-Mcleod,A.; Vernier,P.; Mitchell,S.J., 2008: Decision support framework for assessing alternative mountain pine beetle management strategies on sustainable forest management. We developed a decision support framework that facilitates the assessment of alternative mountain pine beetle (MPB) management strategies on wildlife and other sustainable management indicators. Specifically, the framework permits the evaluation o...

Gjelsteen, A.C.; Ching, B.H.; Meyermann, M.W.; Prager, D.A.; Murphy, T.F.; Berkey, B.D.; Mitchell, L.A., 2008: CT, MRI, PET, PET/CT, and ultrasound in the evaluation of obstetric and gynecologic patients. The role of imaging in obstetrics and gynecology has undergone a revolution over the past few decades. Well-established methods such as endovaginal ultrasound have had a central role in the evaluation of nongravid patients with pelvic pain, as wel...

Anonymous, 1973: Serodiagnosis in invasive amebiasis. La Prensa Medica Mexicana 38(5): 178-181