期刊
PROCESS BIOCHEMISTRY
卷 45, 期 6, 页码 954-960出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.procbio.2010.02.025
关键词
Guehomyces pullulans; beta-galactosidase; Psychrotolerant yeast; Lactose hydrolysis; Antarctica
资金
- National Infrastructure of Natural Resources for Science and Technology Program of China [2005DKA21209]
A psychrotolerant yeast Guehomyces pullulans 17-1 isolated from sea sediment in Antarctica could produce high level (17.2 U/ml) of both extracellular and cell-bound P-galactosidase. The extracellular P-galactosidase in the supernatant of the cell culture of the psychrotolerant yeast G. pullulans 17-1 was purified to homogeneity with a 2.4-fold increase in specific activity as compared to the supernatant by concentration, gel filtration chromatography (Sephadex G-200) and cation-exchange chromatography (CM-Sepharose Fast Flow cation-exchange). The molecular mass of the purified extracellular p-galactosidase was estimated to be 335 kDa. The optimal temperature and pH of the purified beta-galactosidase were 50 C and 4.0, respectively. K-m and V-max values of the purified beta-galactosidase for o-nitrophenyl-beta-D-galactopyranoside were 3.3 mM and 9.2 mu mol/min. Lactose can be converted into glucose and galactose and a large amount of reducing sugar can be released from milk under catalysis of the purified beta-galactosidase. The matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectroscopy identified a peptide ALEEYKK which is the conserved motif of the beta-galactosidases from other yeasts. The results show that the enzyme may have potential applications in food industry. (C) 2010 Elsevier Ltd. All rights reserved.
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