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. 2007 Feb 26;402(Pt 3):429–437. doi: 10.1042/BJ20061457

Figure 1. A high-throughput colorimetric screening procedure.

Figure 1

(A) Fusion expression construct with DCase–α-fragment in the pMAL-c2x vector. The linker between DCase and the α-fragment of β-gal is Gly-Ser-Ala-Gly-Ser-Ala-Ala-Gly-Ser-Gly-Ala-Ser. (B) Photograph of E. coli colonies expressing genes encoding the WT and evolved DCases in liquid medium. (C) Assay of β-gal activity using the substrate ONPG in vitro. A unit of β-gal activity is defined as the amount of enzyme required to hydrolyse 1 μmol of ONPG to O-nitrophenol and D-galactose per min. (D) Native PAGE of soluble fractions of the WT and evolved DCases expressed with α-fragment fusion tag at 37 °C. MU1–MU4, DCase mutants 1–4 as indicated in the main text.