title: Characterization of a metal-dependent D-psicose 3-epimerase from a novel strain, Desmospora sp. 8437.
abstract: The rare sugar d-psicose is an ideal sucrose substitute for food products, due to having 70% of the relative sweetness but 0.3% of the energy of sucrose. It also shows important physiological functions. d-Tagatose 3-epimerase (DTEase) family enzymes can produce d-psicose from d-fructose. In this paper, a new member of the DTEase family of enzymes was characterized from Desmospora sp. 8437 (GenBank accession no. WP_009711885 ) and was named Desmospora sp. d-psicose 3-epimerase (DPEase) due to its highest substrate specificity toward d-psicose. Desmospora sp. DPEase was strictly metal-dependent and displayed maximum activity in the presence of Co(2+). The optimum pH and temperature were 7.5 and 60 °C, respectively. The enzyme was relatively thermostable below 50 °C, but easily lost initial activity when preincubated at 60 °C. The thermostability property was almost not affected by the addition of Co(2+). Desmospora sp. DPEase had relatively high catalysis efficiency for the substrates d-psicose and d-fructose, which were measured to be 327 and 116 mM(-1) min(-1), respectively. The equilibrium ratio between d-psicose and d-fructose of Desmospora sp. DPEase was 30:70. The enzyme could produce 142.5 g/L d-psicose from 500 g/L of d-fructose, suggesting that the enzyme is a potential d-psicose producer for industrial production.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University , 214122 Wuxi, People's Republic of China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Zhang
authors.forename: Dan
authors.initials: D
authors.lastname: Fang
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.forename: Leon
authors.initials: L
authors.lastname: Zhou
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.forename: Wanmeng
authors.initials: W
authors.lastname: Mu
mesh_terms: D003001:Cloning, Molecular; D004795:Enzyme Stability; D005632:Fructose / Q000378:metabolism*; D016936:Gram-Positive Endospore-Forming Bacteria / Q000201:enzymology* / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000378:metabolism*; D010802:Phylogeny; D019998:Racemases and Epimerases / Q000235:genetics* / Q000378:metabolism*; D013696:Temperature
chemical_list: D008670:Metals; C003243:psicose; D005632:Fructose; D019998:Racemases and Epimerases