5'-Nucleotidase activity and substrate affinity in digenetic trematodes.

5'-nucleotidases of eight species of digenetic trematodes were studied using five different substrates. All species showed the following preferential order of substrate affinity; AMP greater than CMP greater than GMP greater than TMP greater than UMP. It was observed that different species occupying similar habitats possessed closely related levels of enzyme activities. The function of 5'-nucleotidases in trematodes is also suggested.