Chloramphenicol Acetyl Transferase Formed by Wild-type and Complementing R Factors in Escherichia coli K12

Summary: Chloramphenicol acetyl transferase (CAT) was purified from Escherichia coli K12 carrying R1 and 222 and from E. coli K12 recA (R1 Cm8 7/R100-99 TcRCmS). The third enzyme has a lower affinity for chloramphenicol and greater heat lability than those specified by R1 and 222, compatible with the enzyme's resulting from interallelic complementation. CAT has a molecular weight of 80000, with subunits of 20000. Material cross reacting with anti-222 CAT serum was detected in CmS mutant cell sonicates.