title: Properties and characterization of a highly purified sarcoplasmic reticulum Ca2+-ATPase from dog cardiac and rabbit skeletal muscle.
abstract: Sarcoplasmic reticulum (SR) Ca2+-ATPase was purified from dog cardiac and rabbit skeletal muscle using Triton X-100 at optimal ratios of 0.5 for cardiac and 0.5 to 1.0 for skeletal SR. The yields of Ca2+-ATPase were 4 to 5 and 1 to 2.2 mg/100 mg of cardiac and skeletal SR protein, respectively. The enzyme activities were 547 +/- 67 mumol ADP/mg/h for cardiac and 1192 +/- 172 mumol ADP/mg/h for skeletal Ca2+-ATPase. Removal of excess Triton X-100 increased the enzyme activities to 719 +/- 70 and 1473 +/- 206 mumol ADP/mg/h, respectively. The residual content of Triton X-100 for cardiac and skeletal Ca2+-ATPase was 20 and 5 mol/mol of enzyme, respectively. Maximum levels of phosphoenzyme were 4.4 +/- 0.2 and 5.6 +/- 0.6 nmol/mg in each case. A single protein band of 100 kDa was obtained for each purified Ca2+-ATPase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preparations were stable at -80 degrees C for 5 months in the presence of 1 mM Ca2+. The phospholipid content of the purified enzyme was 2-fold greater than that of native cardiac and skeletal SR microsomes. Repeated washing of the purified enzyme preparation did not alter the phospholipid content or the specific activities.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004285:Dogs; D008861:Microsomes / Q000201:enzymology; D009132:Muscles / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D017830:Octoxynol; D011092:Polyethylene Glycols; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
chemical_list: D011092:Polyethylene Glycols; D000255:Adenosine Triphosphate; D017830:Octoxynol; D000252:Calcium-Transporting ATPases; D002122:Calcium Chloride