ω-Transaminases (ω-TAs) are widely available for the production of chiral amines and unnatural amino acids. Herein, a rapid spectrophotometric method was developed for screening ω-TAs based on the colored products that can be generated from transamination reactions between aliphatic α-diketones and amino donors catalyzed by ω-TAs. The possible mechanism of the formation of the colored product was investigated according to LC-Q-TOF–MS analysis. Among seven diketones, 2,3-butanedione was selected as the most suitable amino acceptor for colorimetric screening of ω-TAs with high efficiency, high sensitivity, and low background interference. Meanwhile, the absorbance of the colored product generated by 2,3-butanedione catalyzed by ω-TAs in this method was linearly correlated with the results by HPLC analysis. This method was also confirmed to effectively screen ω-TA mutants with high activity towards isopropylamine. Graphical Abstract
Novel photoinitiators (α-DKs) bearing α-dicarbonyl groups as initiating group and aromatic groups as chromophore group were synthesized and developed as visible light type I photoinitiators with high performance for radical photopolymerization of acrylate. α-DKs exhibit good absorption at 405 nm and higher initiation efficiency compared with commercial initiator camphorquinone (CQ) under LED sources. Meanwhile, α-DKs were found to efficiently photosensitize bis (4-methylphenyl) hexafluorophosphate (ION) and initiate both free radical polymerization and cationic polymerization.
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