Some bacterial proteins with affinity for cefotaxime

Abstract

Cefotaxime hydrolysis by β-lactamases is difficult to show by standard techniques (spectrophotometry, iodine and pH stat). There are, however, a number of exceptions, such as the cephalosporinases from Proteus vulgaris, Serratia liquefaciens and Klebsiella oxytoca . More often, only the very sensitive ‘double disk’ technique (Matsuda, Tomioka & Hasegawa, 1976) gives positive results in cefotaxime hydrolysis, as with cefuroxime and cefoxitin. Generally the chromosomally mediated cephalosporinases show a very high affinity Tor cefotaxime ( K i = 0.01 to 1 μM), but the plasmid mediated penicillinases have a very low affinity for this antibiotic ( K i > 1 mM With Escherichia coli K12 penicillin binding proteins (PBP), cefotaxime has a very high affinity for PBP1 and 3, but the binding of radioactive cefotaxime to the proteins of the inner membrane of the same bacteria shows certain new labelled proteins which differ from the PBP.