Bacillus subtilis of secretory expression proline aminopeptidase and application thereof
A Bacillus subtilis, proline aminopeptidase technology, applied in the field of biological enzyme engineering, can solve the problems of low proline aminopeptidase expression efficiency, weak extracellular secretion ability and the like
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Embodiment 1
[0028] The construction method of embodiment 1 proline aminopeptidase Bacillus subtilis
[0029] Primers were designed according to the proline aminopeptidase cDNA sequence (SEQ ID NO.1): upstream primer P1: 5'CG GGATCC ATGGCTGCCAAAC 3'(BamHI); downstream primer P2: 5'CGCG ACGCGT CTAATCAATAGAGTC 3' (MluI). Amplify the target gene with BamHI and MluI restriction sites, double-digest the target gene and plasmid pMA5 with BamHI and MluI, recover and purify the gel, connect overnight at 16°C, transform Escherichia coli JM109 and coat ampicillin-containing LB plate, after the transformants grow out, colony PCR verification is carried out, the positive transformants are cultured and the plasmids are extracted for double-enzyme digestion verification, and the verified recombinant plasmid pMA5-pap is sent to Shanghai Sangon for sequencing.
[0030] The constructed recombinant plasmid pMA5-pap was electrotransformed into Bacillus subtilis WB600, and positive recombinants were scree...
Embodiment 2
[0039] Embodiment 2 The method for secreting and expressing proline aminopeptidase from recombinant Bacillus subtilis
[0040] Pick a single colony of recombinant Bacillus subtilis on the LB plate (containing 50 μg / mL kanamycin) and culture it in 50 mL LB liquid medium (containing 50 μg / mL kanamycin) at 37 ° C for 14 hours at 220 r, then press 1% The inoculum was inoculated in 50mL STB medium (containing 50μg / mL kanamycin) at 37°C and cultured at 220r for 24h. After the fermentation, centrifuge at 8000r, 4°C for 10min, and the obtained fermentation supernatant is the proline aminopeptidase crude enzyme solution, and the measured enzyme activity is 36.0U / mL.
Embodiment 3
[0041] Example 3 Characterization of Proline Aminopeptidase Secreted by Recombinant Bacillus subtilis
[0042]The crude enzyme solution obtained in Example 2 was subjected to two Hitrap Q HP ion-exchange chromatography to obtain proline aminopeptidase that was basically electrophoretic pure, and it was characterized. The results showed that: the optimum reaction temperature was 50°C, It exhibits good temperature stability at and below 50°C; the optimum reaction pH is 7.5, and has good pH stability between pH 6-11; it has strict substrate specificity for proline-p-nitroaniline ; The Michaelis constant Km and the maximum reaction rate Vmax are 0.171mmol L respectively -1 and 55.99 μmol min -1 . The characteristics of the intracellular proline aminopeptidase expressed in recombinant Escherichia coli are basically consistent, indicating that the structure and characteristics of the enzyme have not been changed after secreted expression in Bacillus subtilis. In addition, the sal...
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