(2'-5')Oligoadenylate synthetase in pig spleen: isolation and characterization

A high level of activity of (2'-5')oligoadenylate synthetase (2-5A synthetase) was detected in pig spleens not treated with exogenous interferon. The enzyme recovered from homogenates of pig spleens was partially purified by the use of a combination of ion exchange gels (DEAE-Sephadex and CM-Sepharose) and affinity gels (2',5'-ADP-Sepharose and poly(I):poly(C)-agarose). The specific activity of the final sample was 32,800 nmol AMP polymerized/h/mg protein at 33 degrees C, and the enzyme was able to convert over 80% of ATP into 2-5A after a 24-h incubation; penta-adenylate was the major product (41% of total product). The 2-5A synthetase obtained was eluted from Sephacryl S-200 at around the position of a protein with Mr = 100,000. By using the purified 2-5A synthetase from pig spleens as an antigen, rabbit antiserum to this enzyme was prepared. The antibody bound to protein A-Sepharose absorbed the activity of 2-5A synthetase induced by interferon in pig cells. This result shows that the IFN-induced 2-5A synthetase shares antigenic determinants with the synthetase in spleens. Neither human nor mouse 2-5A synthetase combined with the antibody to porcine 2-5A synthetase. Thus, the antigenic structure of this enzyme is different from species to species.