期刊
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
卷 22, 期 5-6, 页码 307-313出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/S1381-1177(03)00045-6
关键词
Thermophilic bacillus; thermostable lipase; purification; characterization; immobilization
Extracellular thermostable lipase, produced by the thermophilic Bacillus stearothermophilus MC 7 was purified to 19.25-fold with 10.2% recovery. The molecular weight of the purified enzyme determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was shown to be 62 500 Da. The purified enzyme expressed maximum activity at 75-80 degreesC and its half life was 30 min at 70 degreesC. The K-m and V-max were calculated to be, respectively, 0.33 mM and 188 muM min(-1) mg(-1) with p-nitrophenyl palmitate (pNPP) as a substrate. Enzyme activity was inhibited by divalent ions of heavy metals, thiol and serine inhibitors, whereas calcium ion stimulated its activity. The most advantageous method for immobilization was found to be ionic binding to DEAE Cellulose. The enzyme was able to hydrolyze both soluble and insoluble emulsified substrates and was classified as a lipase, expressing some esterase activity as well. (C) 2003 Elsevier Science B.V. All rights reserved.
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