This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Kahn, J. S. Search for Related Content PubMed PubMed Citation Articles by Kahn, J. S. Agricola Articles by Kahn, J. S.

Articles

The Subunit of the Chloroplast Coupling Factor 1 from Euglena gracilis¹

A Possible Role in Controlling ATPase Activity

Department of Biochemistry, North Carolina State University, Raleigh, North Carolina 27650

The coupling factor from chloroplasts (CF₁) of Euglena gracilis Z strain is an active ATPase in situ, and its activity cannot be increased by treatment with trypsin or heating as is the case with the CF₁ from other sources. The smallest subunit of CF₁, the subunit, is supposed to be involved in controlling the ATPase activity. We have devised a simple technique for rapid and large-scale isolation of this subunit. The subunit from Euglena CF₁, although having only a limited inhibitory effect on Euglena CF₁, drastically inhibited the ATPase activity of heat-activated spinach CF₁. The inhibition of spinach CF₁ could be reversed by passage through Sephadex G-50 or by a second heat activation. An antibody to the subunit of Euglena CF₁ cross-reacted only weakly with CF₁ from spinach, Sorghum, Kalanchoë, or Anacystis nidulans, but reacted well with whole Euglena CF₁ in addition to its subunit. The antibody increased the ATPase activity of Euglena and Anacystis CF₁ and of unactivated or partially activated spinach CF₁. The results suggest that the function of the subunit in Euglena CF₁ is similar to its function in CF₁ from other sources. The data also suggest that changes induced in spinach CF₁ by activation involves modifications in subunits other than the one.