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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.