The Subunit Structure of Beef Heart Mitochondrial Adenosine Triphosphatase

Abstract

Each of the five subunits of beef heart mitochondrial adenosine triphosphatase was isolated in homogeneous form following applncation of purification procedures which exploited differences between the various polypeptides in solubility, charge, and molecular weight.13eef heart mitochondrial ATPase or F1' is a cold-labile enzyme which functions as a coupling factor in oxidative phosphorylation (I).Since the first report of the presence of the enzyme in beef heart mitochondria, a number of enzymes which may serve a similar if not ident'ical function in energy conservation mechanisms have been observed in tissues of Tvidely varying origin.These include yeast mitochondria (a), spinach chloroplasts (3), liver mitochondria (4), and the coupling factor from Alcaligenes faecalis (5).In recent years, beginning with the report of MacLennan and Tzagoloff (6), it has become clear that the subunit structure of the beef heart enzyme (7) and liver enzyme (4) is complex.Beef heart FI was shown to contain at least five distinguishable components on acrylamide gel electrophoresis in the presence of dissociating agents (6, 7).In an effort to define more precisely the physical and chemical properties of this important enzyme, we undertook to iso1at.e in homogeneous form each of the various subunits of beef heart Fr.This paper describes the isolation procedures.The physical and chemical properties of each subunit are described in a succeeding paper (8).