Mechanism of ascorbate destruction of opiate stereospecific binding (SSB) in guinea pig brain homogenate
Dunlap III, C.E., Leslie, F.M., Cox, B.M. 1979 Federation Proceedings 38 (3 I), pp. No.135
Ascorbic acid produced a concentration dependent, biphasic destruction of opiate SSB, with maximum destruction occurring at 1 mM, and decreasing at higher ascorbate concentrations. Destruction of SSB by direct chemical reduction was ruled out, since several other reducing agents were without effect. Structural analogs of ascorbic acid were tested. The stereoisomer, D-isoascorbic acid, produced destruction similar to that caused by ascorbate. Dehydroascorbic acid produced only slight loss of SSB, and protected against further destruction of SSB by ascorbate. All other analogs tested were without effect. Oxygen was necessary for ascorbate destruction of SSB, since no loss of SSB was seen in degassed homogenates incubated with ascorbate under nitrogen. Reagents which prevent ascorbate catalyzed lipid peroxide formation were shown also to prevent ascorbate destruction of SSB, and dose-response studies showed that destruction of SSB paralleled ascorbate induced lipid peroxide formation. The mechanism for ascorbate destruction of SSB, therefore, appears to involve modification of some critical receptor moiety by ascorbate catalyzed peroxidation.
Dunlap III, C.E., Leslie, F.M., Cox, B.M. 1979 Federation Proceedings 38 (3 I), pp. No.135