Membrane‐Bound F1 ATPase from Micrococcus Sp. ATCC 398E

Abstract

A chemically reactive ATP analogue, 6‐[(3‐carboxy‐4‐nitrophenyl)thio]‐9‐β‐D‐ribofuranosylpurine 5′‐triphosphate (Nbs⁶ITP) has been synthesized. It has the ability to form stable thioether bonds between the 6‐position of the purine ring and aliphatic mercapto groups. The nucleotide moiety of the reagent has been covalently bound to agarose, via iminobispropylamine and N‐acetyl‐homocysteine as spacer with the purpose of producing an affinity chromatography material. The affinity matrix binds solubilized F₁ ATPase from a crude extract of Micrococcus sp. membranes. Afterwards the enzyme can be selectively eluted from the column at a defined ATP concentration. This method is superior to the conventional purification with respect to speed and convenience of the preparation. The affinity chromatography leads in a one‐step process to the same purity of enzyme, substituting several steps of the conventional method. In addition, the affinity matrix was used for binding studies. Although the presence of Mg²⁺ ions is a prerequisite for the hydrolysis of nucleoside 5′‐triphosphates, evidence is presented indicating that the binding of the nucleoside triphosphates to highly purified F₁ ATPase from Micrococcus sp. appears not to be influenced by Mg²⁺ ion concentrations so far examined.