Ca2+-induced stabilization of the nucleoside 2′- deoxyribosyltransferase from Lactobacillus hilgardii ZJS01: Characteristics and application in nucleosides synthesis

A novel nucleoside 2'-deoxyribosyltransferase (LhNDT) from Lactobacillus hilgardii ZJS01 was cloned and expressed in Escherichia coli BL21 (DE3). The amino acid sequence of LhNDT displayed the highest identity of 26% to other reported NDTs. LhNDT was a monomer as revealed by gel filtration chromatography with or without addition of Ca2+ in elution buffer. This enzyme showed a high activity and stability over a broad pH range and was sensitive to temperature. With the addition of 15mM Ca2+, the thermostability of LhNDT was greatly promoted by 63 times and 46 times at 30°C and 35°C, respectively. With the use of 2'-deoxyuridine as sugar donor at an economic molar ratio of 1:1, 5-aza-2'-deoxycytidine (46%) and 5-fluoro-2'- deoxycytidine (58%) were efficiently synthesized from 5-azacytosine and 5-fluorocytosine, respectively, by LhNDT for 2h.