Change in the ultraviolet spectrum of solubilized Ca2+-dependent ATPase from sarcoplasmic reticulum due to binding with Ca2+ ions.
Solubilized sarcoplasmic reticulum (SSR) was prepared by solubilizing fragmented sarcoplasmic reticulum (FSR) with a nonionic detergent (C12E8) then displacing the detergent with Tween 80, using a DEAE-cellulose column. The UV absorption of SSR decreased reversibly at about 286 and 292 nm on removal of free Ca2+ ions, while no change in the fluorescence spectrum was detectable. On the other hand, the fluorescence intensity of FSR decreased 3-4% on removal of free Ca2+ ions, as previously reported by Dupont [(1976) Biochem. Biophys. Res. Commun. 71, 544-550]. The UV absorption of FSR increased reversibly at about 270-280 nm on removal of free Ca2+ ions, but the rate of the change was very slow (k = about 0.1 min-1).
D000818:Animals; D002118:Calcium; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D009132:Muscles / Q000201:enzymology; D011136:Polysorbates; D011485:Protein Binding; D011487:Protein Conformation; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
D011136:Polysorbates; D000252:Calcium-Transporting ATPases; D002118:Calcium