A novel silver-activated extracellular β-d-fructofuranosidase from Aspergillus phoenicis

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• 作者：Cynthia Barbosa Rustiguel ; Hé ; ctor Francisco Terenzi ; Joã ; o Atí ; lio Jorge ; Luis Henrique Souza Guimarã ; es
• 关键词：Invertase ; Aspergillus phoenicis ; Sucrose ; β ; -Fructofuranosidase ; Fructose ; Silver-activated β ; -fructofuranosidase
• 刊名：Journal of Molecular Catalysis B: Enzymatic
• 出版年：2010
• 出版时间：November 2010
• 年：2010
• 卷：67
• 期：1-2
• 页码：10-15
• 全文大小：330 K

文摘

High levels of extracellular β-d-fructofuranosidase from Aspergillus phoenicis (=Aspergillus saitoi) were obtained when the fungus was grown in Khanna medium supplemented with wheat bran as carbon source, at 40 °C, for 72 h. The extracellular enzyme was purified 12.5-fold to electrophoretic homogeneity, by two chromatographic steps, with a recovery of 7.5 % . The purified invertase is a homodimeric glycoprotein with 1.64 % carbohydrate content, native apparent molecular mass of 155 kDa and identical subunits of 79 kDa. Optima of temperature and pH were 60 °C and 4.5, respectively. The enzyme was stable for up to 1 h at 60 °C. The β-d-fructofuranosidase activity was stimulated by Ag⁺ and K⁺, and inhibited by Hg²⁺, Mn²⁺, Mg²⁺ and Na⁺. The kinetic parameters (K_0.5 and V_max), determined without or with Ag⁺ and using sucrose as substrate, were 59.9 mM, 954.6 U mg⁻¹ protein, and 29.2 mM and 1234.0 U mg⁻¹ protein, respectively. Only glucose and fructose were obtained as products of sucrose hydrolysis. A. phoenicis extracellular invertase is the first silver-activated β-fructofuranosidase described in the literature.