화학공학소재연구정보센터
Applied Biochemistry and Biotechnology, Vol.177, No.8, 1753-1766, 2015
Characteristics of Recombinant Phytase (rSt-Phy) of the Thermophilic mold Sporotrichum thermophile and its applicability in dephytinizing foods
Sporotrichum thermophile produces very low titres of phytase (St-Phy) extracellularly, which is acidstable, thermostable, and protease insensitive with broad substrate specificity, and therefore, the gene encoding phytase (St-Phy) has been cloned and expressed in E. coli. The purified recombinant phytase (rSt-Phy) has the molecular mass of 55 kDa with K-m and Vmax (calcium phytate), k(cat) and k(cat)/K-m of 0.143 mM, 185.05 nmoles mg(-1) s(-1), 5.1 x 10(3) s(-1), and 3.5 x 10(7) M-1 s(-1), respectively. Mg2+ and Ba2+ display slight stimulatory effect on the enzyme, while it is inhibited by other ions to a varied extent. The enzyme is also inhibited by chaotropic agents (guanidinium hydrochloride, potassium iodide, and urea), Woodward's reagent K, and 2,3-butanedione but resistant to both pepsin and trypsin. The rSt-Phy is useful in dephytinization of tandoori and naan (unleavened flat Indian breads), and bread, liberating soluble inorganic phosphate that mitigates anti-nutrient effects of phytic acid.