Regio-selective deprotection of peracetylated sugars via lipase hydrolysis

Purified lipases (via interfacial activation on hydrophobic supports) from different microbial extracts have been evaluated in the regio-selective hydrolysis of peracetylated sugars (peracetylated glucose, ribose and sucrose). Among the enzymes tested, lipases from Candida rugosa (CRL) and from Pseudomonas fluorescens (PFL) exhibited the best properties in these reactions.Then, we have prepared two different immobilized lipase preparations obtained by interfacial activation on hydrophobic supports or by covalent attachment on glutaraldehyde agarose. Interfacially activated lipases exhibited a higher activity than covalently attached enzymes (even by a 100-fold factor), giving the higher yields of mono deacetylated sugars (in some instances by more than a threefold factor) in short reaction times. In the hydrolysis of 1,2,3,5-tetra-O-acetyl-β-d-ribofuranose catalyzed by PFL adsorbed on octyl agarosa, hydrolyzed mainly the 3 position (30% of yield) while the CRL gave the hydrolysis only in position 5 (about 50% of yield).Depending on the enzyme immobilized preparation, we have been able also to obtain selective hydrolysis of 1,2,3,4,6-penta-O-acetyl-α/β-d-glucopyranose obtaining a free hydroxyl group in position 1, 4 or 6. Moreover, selective hydrolysis in the 4′ position of peracetylated sucrose was achieved when the hydrolysis is performed with CRL immobilized on octyl-agarose (yield was 77%).