The interaction between glutathione S-transferase and its antibody α-glutathione S-transferase (B-14) was studied using fluorescence anisotropy, subsequent to glutathione S-transferase bioconjugation with fluorescein-5-maleimide, leading to the determination of the dissociation and association binding constants, Kd and Ka; good binding specificity was observed between glutathione S-transferase and the antibody B-14. The use of spectroscopic techniques, fluorescence anisotropy in particular, is a useful and favourable tool to study biochemical problems.