Biochemical characterization of CTX-M-15 ESβL purified from clinical strain of Klebsiella pneumoniae SJ16

The aim of this study was purification and characterization of CTX-M-15 as a medically important enzyme from locally Klebsiella pneumoniae isolate, CTX-M-15 enzyme was subjected to two purification steps including: precipitation with 80% ammonium sulfate saturation and gel filtration chromatography by using Sepharose-6B column. Specific activity of purified enzyme has been increment up to 21.9 IU/mg with 7.3 purification folds and 69% enzyme recapture. Characterization study of purified enzyme demonstrated that the M.wt. of CTX-M-15 produced by K. pneumoniae was almost 32.2 kDa. The maximal enzyme activity at (pH 7.0), and enzyme settled at pH 6–7. The enzyme also revealed a full activity at a range of temperature between 30–37^oC. Enzyme activity has inhibited powerfully in the existence of EDTA and calcium chloride, when added separately at a constant concentration. Moreover, copper chloride, and ferric chloride also caused a strong inhibition to the enzyme activity while cloxacillin showed a minor effect on enzyme activity.