title: A novel and efficient method for the immobilization of thermolysin using sodium chloride salting-in and consecutive microwave irradiation.
abstract: Sodium chloride salting-in and microwave irradiation were combined to drive thermolysin molecules into mesoporous support to obtain efficiently immobilized enzyme. When the concentration of sodium chloride was 3 M and microwave power was 40 W, 93.2% of the enzyme was coupled to the support by 3 min, and the maximum specific activity of the immobilized enzyme was 17,925.1 U mg(-1). This was a 4.5-fold increase in activity versus enzyme immobilized using conventional techniques, and a 1.6-fold increase versus free enzyme. Additionally, the thermal stability of the immobilized thermolysin was significantly improved. When incubated at 70°C, there was no reduction in activity by 3.5h, whereas free thermolysin lost most of its activity by 3h. Immobilization also protected the thermolysin against organic solvent denaturation. The microwave-assisted immobilization technique, combined with sodium chloride salting-in, could be applied to other sparsely soluble enzymes immobilization because of its simplicity and high efficiency.
authors.affiliation: Research Center for Biomedicine and Health, Hangzhou Normal University, Hangzhou 310012, PR China.
authors.forename: Feifei
authors.initials: F
authors.lastname: Chen
authors.forename: Fangkai
authors.initials: F
authors.lastname: Zhang
authors.forename: Fangchuan
authors.initials: F
authors.lastname: Du
authors.forename: Anming
authors.initials: A
authors.lastname: Wang
authors.forename: Weifang
authors.initials: W
authors.lastname: Gao
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Wang
authors.forename: Xiaopu
authors.initials: X
authors.lastname: Yin
authors.forename: Tian
authors.initials: T
authors.lastname: Xie
mesh_terms: D000085:Acetates / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods*; D004151:Dipeptides / Q000378:metabolism; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008872:Microwaves; D000439:Pentanols / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature; D013820:Thermolysin / Q000378:metabolism*
chemical_list: D000085:Acetates; D004151:Dipeptides; D004800:Enzymes, Immobilized; D000439:Pentanols; D012997:Solvents; C051210:N-benzyloxycarbonyl-aspartylphenylalanine methyl ester; D012965:Sodium Chloride; C032765:tert-amyl alcohol; C007650:ethyl acetate; D013820:Thermolysin