Determination of cytoplasmic 5'-nucleotidase which preferentially hydrolyses 6-hydroxypurine nucleotides in pig, rat and human tissues by immunotitration.

1. Activity of a 5'-nucleotidase which preferentially hydrolyses IMP and GMP was determined by immunotitration in various mammalian tissues. 2. Activity per g of rat tissue was high in testis and spleen and low in skeletal muscle. 3. In human cells, the activity was high in fibroblasts and low in erythrocytes.