Biotransformation of halogenated nucleosides by immobilized Lactobacillus animalis 2′- N -deoxyribosyltransferase

Abstract

An immobilized biocatalyst with 2′-N-deoxyribosyltransferase (NDT) activity, Lactobacillus animalis NDT (LaNDT), was developed from cell free extracts. LaNDT was purified, characterized and then immobilized by ionic interaction. Different process parameters were optimized, resulting in an active derivative (2.6 U/g) able to obtain 1.75 mg/g of 5-fluorouracil-2′-deoxyriboside, an antimetabolite known as floxuridine, used in gastrointestinal cancer treatment. Furthermore, immobilized LaNDT was satisfactorily used to obtain at short reaction times other halogenated pyrimidine and purine 2′-deoxynucleosides such as 6-chloropurine-2′-deoxyriboside (4.9 U/g), 6-bromopurine-2′-deoxyriboside (4.3 U/g), 6-chloro-2-fluoropurine-2′-deoxyriboside (5.4 U/g), 5-bromo-2′-deoxyuridine (2.8 U/g) and 5-chloro-2′-deoxyuridine (1.8 U/g) compounds of pharmaceutical interest in antiviral or antitumor treatments. Besides, increasing the biocatalyst amount 8 times per volume unit allowed obtaining a 5-fold improvement in floxuridine biotransformation. The developed biocatalyst proved to be effective for the biosynthesis of a wide spectrum of nucleoside analogues by employing an economical, simple and environmentally friendly methodology.