Characterization of extracellular beta-lactamases from penicillin G-resistant cells of Streptococcus thermophilus.
In this study, biochemical properties of two extracellular beta-lactamases produced by penicillin-resistant Streptococcus thermophilus cells were investigated. Both beta-lactamases showed specificity for penicillins but not for cephaloridins. The beta-lactamases exhibited different affinities for penicillin G. The one with the higher molecular weight (FI) had a Km value of 3.44 microM and a Vmax value of 8.33 mumol/min/mg of protein, whereas the beta-lactamase with the lower molecular weight (FII) had a Km value of 4.76 microM and a Vmax value of 3.13 mumol/min/mg of protein. Both beta-lactamases were inhibited by iodine, copper sulfate, and iron sulfate but not by EDTA. The optimal pH ranged between 6 and 7, and the optimal temperatures were between 40 and 45 degrees C for both enzymes.
Department of Food Engineering, Middle East Technical University, Ankara, Turkey.
L C
LC
Chirica
T
T
Güray
G C
GC
Gürakan
T F
TF
Bozoğlu
D006863:Hydrogen-Ion Concentration; D010400:Penicillin G / Q000494:pharmacology*; D010403:Penicillin Resistance; D013291:Streptococcus / Q000187:drug effects* / Q000201:enzymology; D013696:Temperature; D001618:beta-Lactamases / Q000378:metabolism*
D001618:beta-Lactamases; D010400:Penicillin G