Bacterial collagen has a wide application prospect in the fields of food and medical materials because of its simple preparation process and low cost, but its application is limited due to the low thermal stability. Based on the truncated Streptococcus pyogenes collagen Scl2 sequence, the recombinant Escherichia coli strains expressing designed collagen with high thermal stability were constructed by inserting proline-rich sequence, and the fermentation conditions of the recombinant strain were optimized. The results showed that the optimal fermentation conditions were as follows: the induced cell concentration was 2.5 with a fermentation time of 24 h; the concentration of IPTG was 1.0 mmol/L and the induction temperature was 35 ℃. Through SDS-PAGE and mass spectrometry identification, high purity collagen was obtained after affinity purification. Circular dichroism experiments showed that the prepared collagen could be correctly folded into triple helix structure. The thermal stability of collagen with proline-rich sequence (Pro-Pro-Gly)10 flanked at the N-and C-terminal was the highest, which is 23 ℃ higher than the original collagen protein Sp2B. This study provides a basis for the design of recombinant collagen materials with high thermal stability.
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