Creating new restriction sites by silent changes in coding sequences.

We present methods for identifying a useful type of DNA site--one that can be mutated to create a new restriction site within a coding region without changing the amino acid sequence. These "latent sites" are abundant--silent mutations creating one of 44 different 6-bp or 8-bp recognition sites were found at relatively high density, roughly one latent site per 9 bp, in the eleven genes tested. Our analysis suggests that site-directed mutagenesis can be used to refashion coding sequences at will for flexible analysis.