Isolation of 2′,3′‐Cyclic Nucleotide 3′‐Phosphodiesterase from Human Brain

The enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (EC 3.1.4.37) has been isolated from an acetone powder of human subcortical white matter. The yield was about 11 mg from 28 g of powder and a specific activity of 213 unitdmg protein was obtained using 2′,3′‐cyclic CMP as the substrate. A major protein band of molecular weight approx. 96,000 was found by gel electrophoresis under nonreducing conditions. However, two distinct protein bands of molecular weight 46,000 ± 1400 and 48,000 ± 1400 were observed when the protein sample was reduced with 10 mM‐dithiothreitol and subjected to electrophoresis in more restrictive 12‐15% polyacrylamide‐SDS gels. This molecular weight is lower than that previously reported for the bovine enzyme. Antibodies against the purified human enzyme have been raised in New Zealand white rabbits.