title: Correlation between hydrolysis of the  -lactam bond of the cephalosporin nucleus and expulsion of the 3-substituent.
abstract: The hydrolysis of two cephalosporins by three different beta-lactamases has been studied. Each enzyme caused a decrease in ultraviolet absorption, a loss of biological activity, and the release of the leaving group from the 3-position. The changes occurred at the same rate and to the same extent with each enzyme, and it is inferred that the loss of the leaving group is a consequence of, and not a prerequisite for, hydrolysis of the beta-lactam ring.
mesh_terms: D000042:Absorption; D001322:Autoanalysis; D001386:Azides / Q000096:biosynthesis; D002511:Cephalosporins / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D002852:Chromatography, Ion Exchange; D004754:Enterobacter / Q000201:enzymology; D004755:Enterobacteriaceae / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology; D006868:Hydrolysis; D007709:Klebsiella / Q000201:enzymology; D010405:Penicillinase / Q000302:isolation & purification / Q000378:metabolism*; D011725:Pyridines / Q000096:biosynthesis; D013053:Spectrophotometry; D014466:Ultraviolet Rays; D047090:beta-Lactams / Q000378:metabolism
chemical_list: D001386:Azides; D002511:Cephalosporins; D011725:Pyridines; D047090:beta-Lactams; D010405:Penicillinase