The prime plasmalemma ATPase of the halophilic algaDunaliella bioculata:purification and characterization

✍ Scribed by Martin Smahel; Antje Hamann; Dietrich Gradmann

• Publisher: Springer-Verlag
• Year: 1990
• Tongue: English
• Weight: 950 KB
• Volume: 181
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00193002

✦ Synopsis

The prime plasmalemma ATPase of the halophilic green alga Dunaliella bioculata has been solubilized by Triton X-100 from a plasmalemma-rich membrane fraction and purified by anion-exchange chromatography. Vanadate-sensitive ATPase activity was totally enriched about 230-fold to a specific activity of approx. 250 nkat.mg protein-1. The presence of Mg 2 + or Mn 2 + is essential for ATP hydrolysis by the enzyme. In addition to an equimolar requirement (1:1 Mg 2+ :ATP), there is further stimulation by Mg 2+ (up to 20 mM) and by (100 mM) monovalent cations (K + -~ NH 2 >Rb + ~-Na + >Cs + >Li + ---choline+). Most anions have no or little effect. With a molecular mass of about 105 kDa for the single subunit, sensitivity to vanadate and N,N'-dicyclohexylcarbodiimide (50% inhibition at about 1 gM and 0.3 mM, respectively), strict ATP-specificity, and an acidic pH optimum, this enzyme shows the typical characteristics of the common type of H +-ATPase in the plasmalemma of higher plants and fungi. These results undermine the hypothesis of a wider distribution of a special (high salt) type of plasmalemma ATPase as found in the marine alga Acetabularia.