On the Inhibition of Aspartate Aminotransferase by Its Antibody
1969 年 66 巻 3 号 p. 321-333
詳細
1969 年 66 巻 3 号 p. 321-333
Studies were performed on the inhibition of aspartate transaminase [EC 2. 6. 1. 1; GOT] isozymes by their corresponding antibodies and the papain [EC 3. 4. 4. l0]-digested fragments of their respective antibodies. The inhibition produced by the fragments (FI and FII) was partially non-competitive with respect to substrates (α-ketoglutarate and aspartate). The transamination reaction between α-ketoglutarate or oxaloacetate and pyridoxamine catalyzed by apo-GOT was also strongly inhibited by the papain-digested fragments. These results suggest that the antigenic determinants are at a different locus from the active site on the GOT molecule.
Anti-s-GOT was purified specifically by the dissociation of the antigen-antibody complex by the addition of high concentration of salt at low pH. Subsequently, the purified antibody could be separated into two types of antibodies on the basis of anti-gen-binding specificity for the suc-s-GOT molecule. One type combines with suc-s-GOT with the formation of precipitates from which it can easily be dissociated. The other type can be recovered from the supernatant solution. Both types are equally inhibitory to native s-GOT, but only that type which combines with suc-s-GOT is capable of inhibiting suc-s-GOT activity. The mechanism of the inhibition of GOT activity by antibody was discussed.
