| Abstract: | We have used alkyl ether analogs of ethanolamine and choline phospholipids as ligands to purify phospholipase A2 (EC 3.1.1.4) from Crotalus adamanteus venom by affinity chromatography. One of the affinity columns was prepared with rac-1-(9-carboxy)nonyl-2-hexadecylglycero-3-phosphocholine linked to AH-Sepharose 4B via the carboxyl group. Specific adsorption of phospholipase A2 to this column was achieved in buffer containing Ca2+, and the enzyme was eluted in buffer containing EDTA. The two enzymes from this venom were prepared in good yield (greater than 90%), and were homogeneous as judged by polyacrylamide gel electrophoresis. Retention of phospholipase A2 did not occur when the initial irrigant was devoid of Ca2+. These results support the compulsory ordered mechanism for this enzyme proposed by Wells ((1972), Biochemistry 11, 1030-1041) on the basis of kinetic considerations. The second affinity support was prepared with 1,2-dihexadecyl-sn-glycero-3-phosphoethanolamine attached through the amine moiety to CH-Sepharose 4B. Specific adsorption of phospholipase A2 to this column did not occur. These data indicate that the phospholipid base group must be accessible to the enzyme for optimal binding, and that modifications in the alkyl side chains are more desirable when designing affinity matrices for purification of enzymes involved in phospholipid metabolism. |
