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. Author manuscript; available in PMC: 2007 Oct 10.
Published in final edited form as: J Mol Biol. 2005 Sep 23;352(3):621–628. doi: 10.1016/j.jmb.2005.07.020

Figure 2.

Figure 2

Randomization of β-galactosidase residues 201, 540 and 604. Complementary primer pairs (arrows) encoding vector sequence (black) or lacZ (colored) were synthesized. The lacZ-specific primers were degenerate (NNK) at codons 201, 540 and 604. The 6his-lacZ-pET28a+ (white circle) was employed as a template in four separate PCR reactions (white bar = vector–201, blue bar = 201–540, green bar = 540–604, red bar = 604–vector). Each PCR product overlapped one or two others in sequence; the four PCR products were combined in a single overlap PCR reaction (reaction 5). The full-length recombinant PCR product was purified, self-ligated and electroporated into E. coli.