Reconstitution of rabbit sarcoplasmic reticulum calcium ATPase in a series of phosphatidylcholines containing a saturated and an unsaturated chain: suggestion of an optimal lipid environment.
The calcium-dependent ATPase from sarcoplasmic reticulum of rabbit has been purified and reconstituted in dispersions containing pure phosphatidylcholines. Each phosphatidylcholine (PC) had palmitate (16:0) at the sn-1 position of glycerol and stearate (18:0), oleate (18:1), linoleate (18:2), arachidonate (20:4), or docosahexaenoate (22:6) at the sn-2 position. The activities and activation energies of the enzyme indicated that the best enzyme function occurred when 16:0-18:1 PC or 16:0-18:2 PC was the lipid in which the ATPase was embedded. Circular dichroism measurements made as a function of temperature suggested that the protein in 16:0-18:0 and 16:0-18:1 PC behaved most like sarcoplasmic reticulum or purified ATPase. The results suggest that there may be an optimal lipid environment for the ATPase which is provided by 16:0-18:1 PC and 16:0-18:2 PC, the two most common lipids of the sarcoplasmic reticulum.
Matthews
P L
PL
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada.
Bartlett
E
E
Ananthanarayanan
V S
VS
Keough
K M
KM
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D003460:Crystallization; D004789:Enzyme Activation; D005227:Fatty Acids / Q000032:analysis; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D009132:Muscles / Q000201:enzymology*; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D012996:Solutions; D013816:Thermodynamics
D005227:Fatty Acids; D008055:Lipids; D010713:Phosphatidylcholines; D012996:Solutions; D000252:Calcium-Transporting ATPases