Table 1.

Mutations in Kan^R Revertants

	Revertants sequenced	First C	Second C	Ratioa
No protein	24	9b	15c	1.7
WT PspGI	52	3	49	16.3

Plasmid pUP41 was heated with or without WT PspGI. Following transformation of the DNA into ung E.coli, independent Kan^R revertants were obtained and sequenced. The location of mutations in independent Kan^R revertants is shown. ‘First C’ and ‘Second C’ refer to cytosines in codon 94 (CCG). With one exception, all the clones contained mutations at one of the two positions. The exception was a clone from the no protein control and contained C to T changes at both the positions. No mutations other than those listed here were seen in a 500 bp window around codon 94.

^aIncludes two C to G and one C to A mutation.

^bIncludes one C to A mutation.

^cThe ratio—(Number of mutations at second C)/(Number of mutations at first C).