5 Hydroxymethyl 2´ deoxycytidine 5´ triphosphate (HMdCTP) is a nucleotide existing in nature as a component of the DNA of T-even phages. The T-even DNA synthesizing machinery is one of the most precise known in nature. T-even phages protect their own DNA from self-degradation, while infecting bacterial cells and degrading the host genome, by the phenomenon of two-step genome modification. In the first step, all phage cytosines are replaced by 5 hydroxymethylcytosine. Bioline has developed a novel method for producing highly purified HMdCTP. Using a unique enzymatic synthesis method, Bioline have been able to mimic the biological steps in the synthesis of HMdCTP from T-even phages. Highly purified HMdCTP can be used in a number of molecular biological applications and offers significant advantages over normal dCTP. For use in Site-Directed Mutagenesis experiments, substitution of dCTP in a wide variety of molecular biology assays, discrimination between the different DNA molecules synthesized in one or several PCR reactions, structural and activity studies of the restriction/modification systems of different organisms, labeling of DNA in vitro, methylation studies, Studies of Hydroxymethylated DNA/protein interaction