Abstract:
:β-Aminobutyric acid (BABA) can be widely used in the preparation of anti-tumor drugs, AIDS drugs, penicillin antibiotics, and plant initiators. However, the efficient, economical, and environmentally friendly production of BABA still faces challenges. Its important production enzyme, aspartase, catalyzes the substrate crotonic acid, and depends on harsh conditions, such as high temperatures and the presence of strong alkali. Here, we modified the surface charge of the enzyme to enable it to become more negatively charged (K19E, N87E, N125D, S133D, Q262E, and N451E; from -60 to -80), reducing its optimal pH from 9.0 to 8.0. The M20 enzyme showed improved specific activity (400.21 mU/mg at pH 8.0; 2.47-fold that of aspartase), and at pH 7.0, its activity increased 3-fold. The thermal stability of the enzyme was also improved. For the production of BABA, a 500 g/L whole-cell transformation was obtained with a 1.41-fold increase in yield, and the final production of BABA reached 556.1 g/L within 12 h. Our method provides a new strategy for modifying the characteristics of the enzyme through the modification of its surface charge, which also represents the first modification of the optimal pH for aspartase.
journal_name
Int J Biol Macromoljournal_title
International journal of biological macromoleculesauthors
Wang Y,Xu M,Yang T,Zhang X,Rao Zdoi
10.1016/j.ijbiomac.2020.08.229subject
Has Abstractpub_date
2020-12-01 00:00:00pages
4165-4172eissn
0141-8130issn
1879-0003pii
S0141-8130(20)34330-0journal_volume
164pub_type
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