tailieunhanh - Báo cáo khoa học: Enzymes for the NADPH-dependent reduction of dihydroxyacetone and D-glyceraldehyde and L-glyceraldehyde in the mould Hypocrea jecorina

The mouldHypocrea jecorina(Trichoderma reesei) has two genes coding for enzymes with high similarity to the NADP-dependent glycerol dehy-drogenase. These genes, calledgld1andgld2, were cloned and expressed in a heterologous host. The encoded proteins were purified and their kinetic properties characterized. | ỊFEBS Journal Enzymes for the NADPH-dependent reduction of dihydroxyacetone and D-glyceraldehyde and L-glyceraldehyde in the mould Hypocrea jecorina Janis Liepins1 2 Satu Kuorelahti1 Merja Penttila1 and Peter Richard1 1 VTT Biotechnology Espoo Finland 2 University of Latvia Institute of Microbiology and Biotechnology Riga Latvia Keywords dihydroxyacetone glycerol dehydrogenase Hypocrea jecorina L-glyceraldehyde NADP-specific glycerol dehydrogenase Correspondence P. Richard VTT Tietotie 2 Espoo PO Box 1000 02044 VTT Finland Fax 358 20 722 7071 Tel 358 20 722 7190 E-mail Received 4 May 2006 revised 7 July 2006 accepted 17 July 2006 doi The mould Hypocrea jecorina Trichoderma reesei has two genes coding for enzymes with high similarity to the NADP-dependent glycerol dehydrogenase. These genes called gldl and gld2 were cloned and expressed in a heterologous host. The encoded proteins were purified and their kinetic properties characterized. GLD1 catalyses the conversion of D-glyceralde-hyde and L-glyceraldehyde to glycerol whereas GLD2 catalyses the conversion of dihydroxyacetone to glycerol. Both enzymes are specific for NADPH as a cofactor. The properties of GLD2 are similar to those of the previously described NADP-dependent glycerol-2-dehydrogenases EC purified from different mould species. It is a reversible enzyme active with dihydroxyacetone or glycerol as substrates. GLD1 resembles EC . It is also specific for NADPH as a cofactor but has otherwise completely different properties. GLD1 reduces D-glyceraldehyde and L-glyceraldehyde with similar affinities for the two substrates and similar maximal rates. The activity in the oxidizing reaction with glycerol as substrate was under our detection limit. Although the role of GLD2 is to facilitate glycerol formation under osmotic stress conditions we hypothesize that GLD1 is active in pathways for sugar acid catabolism such as D-galacturonate .