Isolation and characteristics of scallop sarcoplasmic reticulum with calcium transport activity.
Sarcoplasmic reticulum with calcium transport activity has been isolated from the cross-striated adductor muscle of the scallop, which lives in cold (< or = 20 degrees C) sea water, by using pH 7.0 buffer solution both to homogenize the tissue and to sediment the membrane fraction. The yield of the preparation was 60-100 mg protein from 100 g of the scallop muscle. Ca(2+)-activated ATPase protein of about 100 kDa accounted for 40-50% of the protein preparation. The maximum activities of ATP-dependent, oxalate-facilitated calcium accumulation and Ca(2+)-ATPase were observed at a pH of about 7.0 and temperature of 20-30 degrees C, and their values were about 2 mumol Ca2+/mg of protein/min and about 3 mumol ATP hydrolysis/mg of protein/min, respectively. At 0 degree C, 10-20% of these activities was maintained, while at 37 degrees C, the activities were irreversibly lost. The Ca(2+)-ATPase activity was half-maximally activated at about 0.3 microM [Ca2+]. The ATPase activity exhibited non-Michaelian behavior with respect to ATP, with two different Km values of approximately 10 microM and 0.1-0.3 mM. GTP, CTP, and ITP were also hydrolyzed by the preparation at a rate of 10-30% of that of ATP. The preparation was stored at -80 degrees C with retention of function for about a year.
Abe
M
M
Biological Institute, Faculty of Science, Tohoku University, Miyagi.
Shirakata
Y
Y
Sato
D
D
Konishi
K
K
Watanabe
T
T
Nakamura
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002458:Cell Fractionation / Q000379:methods; D007700:Kinetics; D008854:Microscopy, Electron; D008974:Mollusca; D009132:Muscles / Q000201:enzymology* / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D013816:Thermodynamics; D014461:Ultracentrifugation
D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium