Figure 1.

Schematic illustration of the segmental mutagenesis procedure. The vector is first linearized either at the 5′ or 3′ end of the dehalogenase gene. Progressive exonuclease action and removal of the remaining vector DNA yields two batches of either 3′ or 5′ truncated gene fragments. After assembly of these two ends, the segmental mutagenesis library is ligated into a fresh vector, transformed to E.coli and can be screened for activity.