Inhibitory effects of some antibiotics on activity of carbonic anhydrase from rainbow trout erythrocytes in vitro and in vivo

Carbonic anhydrase (CA) from erythrocytes of rainbow trout Oncorhynchus mykiss was purified by affinity chromatography through a process comprising hemolysate preparation, sepharose-4B-L-tyrosine-sulfanylamide affinity get chromatography, and dialysis. Then the effects of three antibiotics-sodium ampicillin, streptomycin, and trimethoprim plus sulfamethoxazole-on this enzyme were investigated in vitro and in vivo. Inhibition effects were determined in vitro by means of the Lineweaver-Burk and activity-antibiotic regression graphs. The dissociation constant of the enzyme inhibitor complex (K-i) and 50% inhibitory values were 2.16 +/- 0.40 and 1.87 mM for sodium ampicillin, 7.40 +/- 0.310 and 5.21 mM for streptomycin, and 18.50 +/- 0.35 and 9.74 mM for trimethoprim-sulfamethoxazole. The in vivo experiment demonstrated that CA was significantly inhibited by trimethoprim-sulfamethoxazole but not by sodium ampicillin and streptomycin.