Characterization of and drug influence on a calmodulinsensitive phosphodiesterase purified from bovine brain.

A calmodulin-sensitive phosphodiesterase was purified from bovine brain. The purification procedure involved ammonium sulphate fractionation, two chromatographic steps on DEAE-cellulose, gel-filtration on Sephadex G-200, and finally one DEAE-cellulose run, and gave a 2300-fold purification. The purified phosphodiesterase had a Vmax for cyclic AMP of 126 mumol/mg protein X min. and was activated 8-fold by addition of calmodulin and calcium. According to SDS-electrophoresis the purified enzyme contained one major peptide of 59,000 daltons, but the preparation was not homogeneous. The enzyme was characterized kinetically and with regard to the effect of cations, pH temperature, and nucleotides. Furthermore, the influence in vitro on enzyme activity of several classes of drugs, e.g. antidepressants, neuroleptics, antiallergics, platelet inhibitors, and some "reference phosphodiesterase inhibitors" was investigated.