title: Hydrodynamic properties of the chromaffin granule hydrogen ion pumping adenosinetriphosphatase.
abstract: We have determined the hydrodynamic properties of detergent-solubilized ATPase, which is coupled to H+ pumping in bovine adrenal chromaffin granules, by sedimentation equilibrium centrifugation and gel permeation chromatography. The protein solubilized with detergent containing phosphatidylserine sediments as a particle of 264,000 daltons and partial specific volume 0.829 cm3/g. Assuming a protein v of 0.73 and using the v measured for detergent and lipid mixed micelles of 0.93 cm3/g, we calculated that the protein component has a mass of 134,000 daltons and that the equivalent of approximately 1.5 micelles of detergent are bound per particle. The particle exhibits a Stokes radius of 43 A, which, together with the calculated particle volume, indicates an axial ratio close to 1. We conclude that the ATPase is an intrinsic membrane protein with a structure very different from that of mitochondrial F1F0 ATPase.
mesh_terms: D000313:Adrenal Medulla / Q000201:enzymology; D000818:Animals; D002417:Cattle; D002837:Chromaffin Granules / Q000201:enzymology*; D002838:Chromaffin System / Q000201:enzymology*; D007425:Intracellular Membranes / Q000201:enzymology*; D007700:Kinetics; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D006180:Proton-Translocating ATPases