Epoxide hydrolases from yeasts and other sources: versatile tools in biocatalysis

Major characteristics, substrate specificities and enantioselectivities of epoxide hydrolases from various sources are described. Epoxide hydrolase ac tivity in yeasts is discussed in more detail and is compared with activitie s in other microorganisms. Constitutively produced bacterial epoxide hydrol ases are highly enantioselective in the hydrolysis of 2,2-and 2,3-disubstit uted epoxides. A novel bacterial limonene-1,2-epoxide hydrolase, induced by growth on monoterpenes, showed high activities and selectivities in the hy drolysis of several substituted alicyclic epoxides. Constitutively produced epoxide hydrolases are found in eukaryotic microorganisms. Enzymes from fi lamentous fungi are useful biocatalysts in the resolution of aryl- and subs tituted alicyclic epoxides. Yeast epoxide hydrolase activity has been demon strated for the enantioselective hydrolysis of various aryl-, alicyclic- an d aliphatic epoxides by a strain of Rhodotorula glutinis. The yeast enzyme, moreover, is capable of asymmetric hydrolysis of meso epoxides and perform s highly enantioselective resolution of unbranched aliphatic 1,2-epoxides. Screening for other yeast epoxide hydrolases shows that high enantioselecti vity is restricted to a few basidiomycetes genera only. Resolution of very high substrate concentrations is possible by using selected basidiomycetes yeast strains. (C) 1999 Elsevier Science B.V. All rights reserved.