The action of the three kinds of the third generation cephalosporin-class new medicine, cefepime hydrochroride, cefpiramide and ceftizoxime, with HSA and BSA was studied at different temperature through fluorescence method. First the binding constants were calculated by using fluorescence quenching and enhancement theoretical equations respectively, then their thermodynamic functions were also calculated respectively. Because the K_A corresponding to the different theoretical equations are not completely the same, the thermodynamic parameters calculated from above are different too. In this paper, the difference among these thermodynamic data obtained from the different theoretical equations have been analysed and the result shows that the thermodynamic data, deduced from fluorescence enhancement Eq. (4) are more reasonable. So we propose that even when the fluorescence quenching action of the acceptor-substrate is studied, more conforming to reality results can be obtained by using the fluorescence enhancement Eq. (4).

Key words: fluorescence enhancement and quenching, serum albumin, the third generation Cephalosporin-class new medicine, thermodynamic analysis