the resin is washed with water until clear washing waters are obtained about 2 litres the resin with the immobilised enzymatic activities is then preserved at 4 u00b0 c in 0 1 m potassium phosphate buffer at ph 7 5 the catalytic activity of the enzymes upase and pnpase coupled in the resin with immobilised cells is determined with a transglycosylation reaction carried out using standardised conditions 200 g or 400 g of solid carrier with immobilised cells containing the upase enzymatic activity and the pnpase enzymatic activity wet weight as described in the preceding point is added to 10 ml of reaction mixture the reaction is carried out with the following solution 40 mm arabinofuranosyluracil ara u 40 mm adenine 30 mm monobasic potassium phosphate u2014 ph 7 2 at a temperature thermostated at 60 u00b0 c after 60 minutes at 60 u00b0 c the reaction is stopped by diluting the reaction 1 50 in water the percentage of adenine converted into arabinofuranosyladenine ara a is determined by analysing an aliquot of the reaction mixture with a high performance liquid chromatograph hplc equipped with a nucleosil 100 5 column macherey nagel of 250 u00d7 4 6 mm size eluting with a 10 mm monobasic potassium phosphate buffer u2212 6 methanol the catalytic activity of the coupled upase and pnpase enzymes catalytic activity of transglycosylation is expressed in units wet g micromoles per minute of adenine converted to form ara a in the assay conditions wet weight gram of cell paste and is calculated with respect to the adenine conversion percentage 4 fermentation of the cells containing the upase enzymatic activity or the pnpase enzymatic activity the recombinant strains exp05 03 coding for the upase enzyme and exp05 04.