摘要
1,3-propanediol (1,3-PD) is an important material for chemical industry,and there has been always much interest in the production of 1,3-PD using all possible routes. The genes encoding glyc-erol dehydratase (GDHt) from Citrobacter freundii,Klebsiella pneumoniae and metagenome were cloned and expressed in E. coli. All glycerol dehy-dratases but the one from metagenome could be detected to show enzyme activities. In order to im-prove the enzymatic properties of GDHts,the genes encoding α and β-γ subunits were cloned,and the enzyme characteristics were evolved by rational de-sign based on their 3D structures which were con-structed by homology modeling. Six heteroenzymes were obtained by swapping the α subunit genes of these three different-source-derived GDHts. The pH,thermal stability and Vmax of some heteroenzymes were dramatically improved by 2―5 times compared with the wild one (GDHtKP). The GDHt cloned from metagenome,originally proved to be with no enzyme activity,was converted into active enzyme by swap-ping its subunits with other different GDHts. In addi-tion,the effect of subtle 3D structural changes on the properties of the enzyme was also observed.
1,3-propanediol （1,3-PD） is an important material for chemical industry, and there has been always much interest in the production of 1,3-PD using all possible routes. The genes encoding glycerol dehydratase （GDHt） from Citrobacter freundii, Klebsiella pneumoniae and metagenome were cloned and expressed in E. coil All glycerol dehydratases but the one from metagenome could be detected to show enzyme activities. In order to improve the enzymatic properties of GDHts, the genes encoding a and β-γ subunits were cloned, and the enzyme characteristics were evolved by rational design based on their 3D structures which were constructed by homology modeling. Six heteroenzymes were obtained by swapping the a subunit genes of these three different-source-derived GDHts. The pH, thermal stability and Vmax of some heteroenzymes were dramatically improved by 2--5 times compared with the wild one （GDHtKP）. The GDHt cloned from metagenome, originally proved to be with no enzyme activity, was converted into active enzyme by swapping its subunits with other different GDHts. In addition, the effect of subtle 3D structural changes on the properties of the enzyme was also observed.
