Inhibitory effects of some antibiotics on glucose 6-phosphate dehydrogenase from the erythrocytes of rainbow trout (Oncorhynchus mykiss Walbaum, 1792) were investigated. For this purpose, initially erythrocyte glucose 6-phosphate dehydrogenase was purified 1271.19-fold in a yield of 70.40% by using ammonium sulfate precipitation and 2',5'-ADP Sepharose 4B affinity gel. A constant temperature (+4 ºC) was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. This method was utilized for all kinetic studies. Thiamphenicol, amikacin, gentamicin, and netilmicin were used as antibiotics. All the antibiotics exhibited inhibitory effects on the enzyme. Ki constants for glucose 6-phosphate dehydrogenase were found by means of Lineweaver-Burk graphs. While thiamphenicol and amikacin showed competitive inhibition, gentamicin and netilmicin displayed noncompetitive inhibition. In addition, I50 values of the antibiotics were determined by plotting activity % vs. [I].

Inhibitory effects of some antibiotics on glucose 6-phosphate dehydrogenase from the erythrocytes of rainbow trout (Oncorhynchus mykiss Walbaum, 1792) were investigated. For this purpose, initially erythrocyte glucose 6-phosphate dehydrogenase was purified 1271.19-fold in a yield of 70.40% by using ammonium sulfate precipitation and 2',5'-ADP Sepharose 4B affinity gel. A constant temperature (+4 ºC) was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. This method was utilized for all kinetic studies. Thiamphenicol, amikacin, gentamicin, and netilmicin were used as antibiotics. All the antibiotics exhibited inhibitory effects on the enzyme. Ki constants for glucose 6-phosphate dehydrogenase were found by means of Lineweaver-Burk graphs. While thiamphenicol and amikacin showed competitive inhibition, gentamicin and netilmicin displayed noncompetitive inhibition. In addition, I50 values of the antibiotics were determined by plotting activity % vs. [I].