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Characteristics of Recombinant Phytase (rSt-Phy) of the Thermophilic mold Sporotrichum thermophile and its applicability in dephytinizing foods
- Ranjan, Bibhuti, Singh, Bijender, Satyanarayana, T.
- Applied biochemistry and biotechnology 2015 v.177 no.8 pp. 1753-1766
- Escherichia coli, Myceliophthora thermophila, barium, breads, genes, guanidinium, ions, magnesium, molecular weight, pepsin, phosphates, phytases, phytic acid, potassium iodide, substrate specificity, thermal stability, trypsin, urea
- 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 Kₘ and Vₘₐₓ (calcium phytate), kcₐₜ and kcₐₜ/Kₘ of 0.143 mM, 185.05 nmoles mg⁻¹ s⁻¹, 5.1 × 10³ s⁻¹, and 3.5 × 10⁷ 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.