Reaction products of chloramphenicol acetyltransferases from enterobacteria and Haemophilus influenzae.

The reaction products of Types I, II and III chloramphenicol acetyltransferases (CATs) from reference strains of Escherichia coli and Type II CATs from clinical isolates of Haemophilus influenzae were examined by HPLC. Types I and III CATs produced 1, 3 diacetylchloramphenicol at pH 6.8 and 7.8 whereas Type II enzymes failed to produce this diester at either pH. All the CATs produced monoacetylchloramphenicol at both pH values. Neither mono- nor di-acetylchloramphenicol was stable. Breakdown of enzymically-produced mono- and di-esters proceeded more rapidly at pH 7.8 than at pH 6.8. Similar breakdown behaviour was observed with synthetically manufactured 1, 3 diacetylchloramphenicol.