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Purification and Properties of Exo-Inulinases from Penicillium janczewskii Growing on Distinct Carbon Sources

Rosemeire A. B. Pessoni, Marcia R. Braga and Rita de Cássia L. Figueiredo-Ribeiro
Mycologia
Vol. 99, No. 4 (Jul. - Aug., 2007), pp. 493-503
Stable URL: http://www.jstor.org/stable/20444864
Page Count: 11
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Purification and Properties of Exo-Inulinases from Penicillium janczewskii Growing on Distinct Carbon Sources
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Abstract

Penicillium janczewskii, isolated from the rhizosphere of Vernonia herbacea, grows rapidly on media containing either sucrose or inulin, although inulin more than sucrose induced the production of inulinases. Three different extracellular β-fructofuranosidases (two inulinases and one invertase) were purified from fungal cultures grown on sucrose or inulin, through precipitation with ammonium sulfate, and anion-exchange, hydrophobic interaction and gel filtration chromatographies. The optimum temperature of the three enzymes was approximately 60 C, optimum pH 4-5.5 and apparent molecular mass of 80 kDa. $\text{K}_{\text{m}}$ and $\text{V}_{\text{max}}$ values determined for invertase on sucrose were respectively 3.7 10⁻⁴ M and 7.9 10⁻² μmol/min/mL, and on inulin 6.3 10⁻² M and 2.09 10⁻² μmol/min/mL. The values of $\text{k}_{\text{m}}$ for the two inulinases were 8.11 10⁻⁴ and 2.62 10⁻³ M, being lower for inulin when compared to those obtained for sucrose. The inulinases did not produce oligofructans from inulin, indicating they are primarily exoinulinases. The differences found in inulinase induction patterns when inulin or sucrose was used seem to be related to modifications on the enzyme properties, mainly concerning substrate affinity.

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