Preparation of clear solutions of reconstituted acetylcholinesterase. Effect of ionic strength and lipid/protein ratio.
The detergent-soluble globular dimer of acetylcholinesterase from Torpedo californica was reconstituted through dialysis into preformed egg phosphatidylcholine vesicles. The formation of the enzyme-lipid complexes depended on the ionic strength of the dialysis buffer as well as the molar lipid/protein ratio (R). The enzyme was unstable at I less than 0.05; increasing the ionic strength increased the size of the complex. A too low R value (e.g. 1000) would promote self-aggregation of the enzyme and produce heterogeneous complexes, especially at high I values. On the other hand, a too high R value (e.g. greater than 5000) favored the formation of large enzyme-lipid complexes; their solutions were too turbid for optical studies. The enzyme reconstituted at I = 0.07 and R = 4000 gave a clear solution and showed no artifacts due to light scattering. The conformation based on circular dichroism and enzymatic activity of the detergent-soluble enzyme were unchanged upon reconstitution. The reconstituted enzyme in lipid vesicles seemed to be slightly more stable against thermal denaturation than the protein in sodium cholate solution.
Gan
L
L
Cardiovascular Research Institute, University of California, San Francisco.
Yang
J T
JT
Wu
C S
CS
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D002942:Circular Dichroism; D003902:Detergents; D004557:Electric Organ / Q000201:enzymology; D008081:Liposomes; D010710:Phosphates / Q000032:analysis; D010713:Phosphatidylcholines / Q000494:pharmacology*; D011487:Protein Conformation; D012996:Solutions; D013816:Thermodynamics; D014101:Torpedo
D003902:Detergents; D008081:Liposomes; D010710:Phosphates; D010713:Phosphatidylcholines; D012996:Solutions; D000110:Acetylcholinesterase