Biochemical characterization of a novel l-asparaginase from Bacillus megaterium H-1 and its application in French fries

A novel ansZ gene, encoding a putative l-asparaginase II from Bacillus megaterium H-1 (BmAase), was cloned and expressed in Escherichia coli. The recombinant enzyme showed high activity (44.7IU/mg) with negligible glutaminase activity and was purified to homogeneity using one-step nickel-affinity ch...

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Bibliographic Details
Published in:	Food research international Vol. 77; pp. 527 - 533
Main Authors:	Zhang, Sunyan, Xie, Yajuan, Zhang, Chong, Bie, Xiaomei, Zhao, Haizhen, Lu, Fengxia, Lu, Zhaoxin
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 01-11-2015
Subjects:	Acrylamide Bacillus megaterium Characterization l-Asparaginase Characterization Nessler's reagent (PubChem CID: 24542) Acrylamide Phenylmethanesulfonyl fluoride (PubChem CID: 4784) 2-Mercaptoethanol (PubChem CID:1567) l-Asparagine (PubChem CID: 6267) Acrylamide (PubChem CID: 6579) Isopropyl-beta-D-thiogalactopyranoside (PubChem CID: 656894) Kanamycin (PubChem CID: 6032) l-Asparaginase Trichloroacetic acid (PubChem CID: 6421) Bacillus megaterium
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Summary:	A novel ansZ gene, encoding a putative l-asparaginase II from Bacillus megaterium H-1 (BmAase), was cloned and expressed in Escherichia coli. The recombinant enzyme showed high activity (44.7IU/mg) with negligible glutaminase activity and was purified to homogeneity using one-step nickel-affinity chromatography. The molecular weight of BmAase was 39.63kDa by MALDI-TOF MS. The optimum pH and temperature for BmAase activity were 7.0 and 40°C, respectively. The enzyme was stable in the pH range of 5.0–8.0 and exhibited more than 70% and 55% retention of activity following 12h of incubation at 60 and 70°C, respectively. The melting temperature of the protein determined by DSC was 51.3°C. The KM and Vmax values of BmAase were, respectively, 0.80mM and 1.58IU/μg for its natural substrate l-asparagine. Acrylamide formation upon frying of potato strips treated with BmAase was about 92% lower than in untreated potato strips. These results reveal the potential of this enzyme for use in the food processing industry. •A novel ansZ gene encoding l-asparaginase from Bacillus megaterium H-1 (BmAase) was isolated and characterized.•BmAase showed highly specific activity across a wide pH range and significant temperature stability.•BmAase could reduce almost all amount of acrylamide formed during the frying process.
ISSN:	0963-9969 1873-7145
DOI:	10.1016/j.foodres.2015.08.031