Cynthia Barbosa Rustiguel, Arthur Henrique Cavalcanti de Oliveira, Héctor Francisco Terenzi, João A. Jorge, Luis Henrique Souza Guimarães
The filamentous fungus A. phoenicis produced high levels of ?-D-fructofuranosidase (FFase) when grown for 72 hrs under Solid-State Fermentation (SSF), using soy bran moistened with tap water (1:0.5 w/v) as substrate/carbon source. Two isoforms (I and II) were obtained, and FFase II was purified 18-fold to apparent homogeneity with 14% recovery. The native molecular mass of the glycoprotein (12% of carbohydrate content) was 158.5 kDa with two subunits of 85 kDa estimated by SDS-PAGE. Optima of temperature and pH were 55�C and 4.5. The enzyme was stable for more than 1 hr at 50�C and was also stable in a pH range from 7.0 to 8.0. FFase II retained 80% of activity after storage at 4�C by 200 hrs. Dichroism analysis showed the presence of random and ?-sheet structure. A. phoenicis FFase II was activated by Mn2+, Mg2+ and Co2+, and inhibited by Cu2+, Hg2+ and EDTA. The enzyme hydrolyzed sucrose, inulin and raffinose. Kd and Vmax values were 18 mM and 189 U/mg protein using sucrose as substrate.
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