3.2.2.8 a pyrimidine nucleoside + H2O - 3.2.2.8 additional information the enzyme is required for recycling of nitrogenous bases 3.2.2.8 N-D-ribosylpyrimidine - 3.2.2.8 N-ribosylpurine + H2O - 3.2.2.8 N-ribosylpyrimidine + H2O preferred substrate