Total biosynthesis of deoxynucleoside triphosphates using deoxynucleoside monophosphate kinases for PCR application.

Polymerase chain reaction (PCR) and other PCR applications for DNA synthesis require deoxynucleoside triphosphates (dNTP) as the essential precursors and substrates. Currently, the dNTP is commercially produced by a chemical method which is environmentally hazardous and costly due to its low yields in both the synthetic reaction and purification processes. In this study, a enzyme technology for the total integrated biosynthesis of all dNTP components is presented. The bioprocess technology developed and reported here involves two sequential enzymatic phosphorylation reactions coupled with the cofactor regeneration starting from deoxynucleoside monophosphates (dNMP) to deoxynucleoside diphosphates (dNDP) in the first reaction step and to dNTP in the second reaction step in the same bioreactor. The four genes encoding these deoxynucleoside monophosphate kinases were cloned into the recombinant E. coli and expressed using the recombinant E. coli strains. The reaction mechanisms and kinetics of the four kinase enzymes are studied and reported. The total enzymatic syntheses of the four dNTP products were carried out in four separate operations under the high substrate concentrations which emulate the practical application. The optimal process conditions were carefully investigated and complete conversion of dNMP to dNTP at high substrate concentration have been achieved. The purity and quality of dNTP products obtained from this work were analyzed and found to be at least equivalent or better than the commercially available dNTP products. The PCR application of dNTP products obtained from this work were also evaluated for isolating and amplifying genes of different sizes from different organisms. The PCR performance test also showed an equivalent quality as compared to the commercially available dNTP. The bioprocess technology developed and reported here for production of dNTP will provide economically competitive and environmentally friendly viable technology for the industry and research community as compared to the chemical technology currently in use.