The use of a thermostable signature amidase in the resolution of the bicyclic synthon (rac)-γ-lactam

The resolution of the bicyclic synthon (rac)-γ-lactam (2-azabicyclo[2.2.1]hept-5-en-3-one) is an important step in the synthesis of a group of chemotherapuetic agents known as carbocyclic nucleosides. The archaeon Sulfolobus solfataricus MT4 produces a thermostable γ-lactamase that has a high sequence homology to the signature amidase family of enzymes. It shows similar inhibition patterns of amidases towards benzonitrile, phenylmethylsulfonyl fluoride and heavy metals such as Hg2+, and is activated by thiol reagents. The enzyme selectively cleaves the (+)-enantiomer from a racemic mix of γ-lactam. It also exhibits general amidase activity by cleaving linear and branched aliphatic and aromatic amides. The enzyme catalyses the synthesis of benzoic hydrazide from benzamide preferentially to benzamide cleavage in the presence of excess hydrazine. This enzyme has potential for use in industrial biotransformations in the production of both carbocyclic nucleosides and hydrazides.