J. Biochem, 1992, Vol. 112, No. 6 822-827
© 1992 Japanese Biochemical Society
research-article |
Isolation and Characteristics of Scallop Sarcoplasmic Reticulum with Calcium Transport Activity
*Biological Institute, Faculty of Science, Tohoku University Aoba-yama, Aoba-ku, Sendai, Miyagi 980
**Faculty of Liberal Arts, Tohoku Gakuin University Sendai, Miyagi 981–31
***Department of Biological Science, College of General Education, Tohoku University Kawauchi, Sendai, Miyagi 980
1To whom correspondence should be addressed
Sarcoplasmic reticulum with calcium transport activity has been isolated from the cross-striated adductor muscle of the scallop, which lives in cold (
20°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. Ca2+-activated ATPase protein of about 100 kDa accounted for 40–50precnt; of the protein preparation. The maximum activities of ATP-dependent, oxalate-facilitated calcium accumulation and Ca2+-ATPase were observed at a pH of about 7.0 and temperature of 20– 30°C, and their values were about 2 µmol Ca2+/mg of protein/min and about 3 itmol ATP hydrolysis/mg of protein/min, respectively. At 0°C, 10–20% of these activities was maintained, while at 37°C, the activities were irreversibly lost. The Ca2+-ATPase activity was half-maximally activated at about 0.3µM [Ca2+]. The ATPase activity exhibited non-Michaelian behavior with respect to ATP, with two different Km values of 
10 µM 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°C with retention of function for about a year.