Abstract
A novel dextranase was purified from Penicillium cyclopium CICC-4022 by ammonium sulfate fractional precipitation and gel filtration chromatography. The effects of temperature, pH and some metal ions and chemicals on dextranase activity were investigated. Subsequently, the dextranase was used to produce dextran with specific molecular mass. Weight-average molecular mass (Mw) and the ratio of weight-average molecular mass/number-average molecular mass, or polydispersity index (Mw/Mn), of dextran were measured by multiple-angle laser light scattering (MALS) combined with gel permeation chromatography (GPC). The dextranase was purified to 16.09-fold concentration; the recovery rate was 29.17%; and the specific activity reached 350.29 U/mg. Mw of the dextranase was 66 kDa, which is similar to dextranase obtained from other Penicillium species reported previously. The highest activity was observed at 55 °C and a pH of 5.0. This dextranase was identified as an endodextranase, which specifically degraded the α-1,6 glucosidic bonds of dextran. According to metal ion dependency tests, Li+, Na+ and Fe2+ were observed to effectively improve the enzymatic activity. In particular, Li+ could improve the activity to 116.28%. Furthermore, the dextranase was efficient at degrading dextran and the degradation rate can be well controlled by the dextranase activity, substrate concentration and reaction time. Thus, our results demonstrate the high potential of this dextranase from Penicillium cyclopium CICC-4022 as an efficient enzyme to produce specific clinical dextrans.
Highlights
Dextranase (1,6-α-D-glucan-6-glucanohydrolase; E.C. 3.2.1.11) is an inducible enzyme and can specially catalyse the endohydrolysis of α-(1,6)-D-glycoside linkages at random sites of dextran
Dextran molecules produced by dextranase with relatively low weight-average molecular mass (Mw) of 20–70 kDa can be used as blood extenders and those with molecular weight (Mw) of 6–8 kDa can form complexes with iron to treat severe anaemia [4]
We obtained a novel dextranase from Penicillium cyclopium CICC-4022
Summary
Dextranase (1,6-α-D-glucan-6-glucanohydrolase; E.C. 3.2.1.11) is an inducible enzyme and can specially catalyse the endohydrolysis of α-(1,6)-D-glycoside linkages at random sites of dextran. Dextranase has been widely used in the production of specific clinical dextrans [2,3]. Dextran molecules produced by dextranase with relatively low weight-average molecular mass (Mw) of 20–70 kDa can be used as blood extenders and those with Mw of 6–8 kDa can form complexes with iron to treat severe anaemia [4]. Bacteria and fungi are two of the main sources to produce dextranases [9]. Wu et al [4] obtained a dextranase from Hypocrea lixii F1002, of which the specific enzyme activity was 2782 U/mg. Zhang et al [13] screened Talaromyces pinophilus H6 from the soil, which was found to be stable at 35–60 ◦C and pH of 3.0–10.0 This special dextranase displayed activity as high as 14,894 U/mg
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