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Isolation,purification and some properties of invertase from sweet potato

Tang Yunming, Li Nan, Chen Dingfu

Department of Life Sciences,Southwest China Normal University.Chongqing 630715,Sichuan

Abstract

Invertase was isolated and purified from the extract of sweet potato (Ipomeoa batatas Lam.) leaves by ammonium sulphate precipitation, DEAE-Sepharose column chromatography, and Sephacry1 S-200 gel filtration. It was purified 282.1-fold with an activity recovery of 22.7%. The purified invertase preparation was homogeneous as judged by polyacrylamide gel electrophoresis and SDS-PAGE. The molecular weight of the native invertase was determined by gel filtration to be 79.4 kD. The invertase consists of two identical subnuits with an apparent molecular weight of 39.8 kD as determined by SDS-PAGE(Fig.3B).The invertase followed typical Michaelis-Menten Kinetics with an apparent K_(m) of 12 mmol/L for sucrose. The V_(max) of the invertase was 99.5 mg reducing sugar mg~(-1) protein h~(-1). The enzyme was shown to be stable between pH 4. 0 and 6. 0 and to have an optimum pH of 5.0 for its activity. The temperature optimum was 60℃.

Key words: Sweet potato leaves;Invertase;Purification;Properties

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Citing This Article：

Tang Yunming, Li Nan, Chen Dingfu. Isolation,purification and some properties of invertase from sweet potato. Acta Physiol Sin 1996; 48 (1): (in Chinese with English abstract).