N-TERMINAL AMINO-ACID-SEQUENCE OF BETA-LACTAMASE FROM SHIGELLA-FLEXNERI UCSF-129

A beta-lactamase (EC 3.5.2.6 penicillinase, penicillin amino beta-lact am-hydrolase) was purified from Shigella flexneri USCF-129 by an effic ient two-stage procedure involving chromatography in Sephadex G-75 and HPLC on a C-18-reverse phase column. The homogeneity of the purified enzyme was confirmed by capillary zone electrophoresis (CZE), HPLC ele ctrospray mass spectrometry (LC-ESMS) and amino acid sequence analyses . The highly purified enzyme was a monomeric protein with a molecular mass of 28.903 +/- 2 Da, as determined by LC-ESMS. The amino acid sequ ence of the first 49 N-terminal residues of this beta-lactamase reveal ed 100% similarity with the mature forms of the plasmid coded Escheric hia coli enzymes (plasmid pBR 322 and R6K) a TEM-type beta-lactamase.