Extraction, purification and characterization of invertase from Candida guilliermondii isolated from peach solid wastes/ Extracao, purificacao e caracterizacao da invertase de Candida guilliermondii isolada de residuos solidos de pessego

The best conditions for in vitro sucrose hydrolysis based on invertase from Candida guilliermondii (ICg) were studied and the kinetic parameters [K.sub.M], [V.sub.max], and thermal stability of ICg were determined. Candida guilliermondii (Cg) yeast isolated and lyophilized from peach solid wastes was identified using the API 20C AUX method. Subsequently, the Cg was submitted to an autolysis process using NaHC[O.sub.3] at 200 mM under 200 rpm stirring and 40[degrees]C for 24 h. The enzyme extracts obtained were recovered through precipitation with acetone followed by dialysis and ion-exchange chromatography. The extract purified through precipitation with acetone had activity of 27.7 U.[mg.sup.-1] and 56% recovery whereas the chromatography process yielded 46.5 U.[mg.sup.-1] and 44.8%. The optimal sucrose hydrolysis conditions were pH 5.0 and 50[degrees]C, resulting in KM of 30.5 mM and 28.7 mM sucrose, respectively, at 25[degrees]C and 50[degrees]C, both with Michaelian behavior. Thermal inactivation of ICg exhibited first-order apparent kinetics and its residual activity was typically linear between 40[degrees]C and 70[degrees]C. Three isoenzymes were detected through electrophoresis. Index terms: Yeast; autolysis; isoenzymes; inverted sugar. Estudaram-se as melhores condicoes de hidrolise da sacarose in vitro a partir da invertase de Candida guilliermondii (ICg), tambem se determinou os parametros cineticos [K.sub.M], [V.sub.max] e a estabilidade termica da ICg. A levedura Candida guilliermondii (Cg) extraida, isolada e liofilizada de residuo de pessego foi identificada usando o metodo API 20C AUX. Posteriormente, a levedura Cg foi submetida a um processo de autolise, usando NaHC[O.sub.3] a 200 mM sob agitacao a 200 rpm e 40[degrees]C, por periodo de 24 horas. Os extratos enzimaticos obtidos foram recuperados por precipitacao com acetona seguido de dialise e cromatografia de troca ionica. O extrato purificado por precipitacao com acetona teve a atividade de 27,7 U.[mg.sup.-1] e 56% de recuperacao, sendo que, por cromatografia, obtiveram-se 46,5 U.[mg.sup.-1] e 44,8%. As condicoes otimas na hidrolise da sacarose foram pH de 5,0 e 50[degrees]C, apresentando KM de 30,5/mM e 28,7 mM de sacarose, respectivamente, a 25[degrees]C e a 50[degrees]C, ambas com comportamento Michaeliano. A inativacao termica da ICg mostrou uma cinetica aparente de primeira ordem, e sua atividade residual foi tipicamente linear entre 40[degrees]C-70[degrees]C. Por meio de eletrofore