Studies on the Inactivation of Antibiotics in Rat Liver Homogenate

Part II. Some Model Experiments to Analyse the Recurrence Phenomenon

Abstract

Model experiments using metal ions and human albumin dissolved in phosphate buffer were carried out in order to analyse the mechanism of the recurrence of PC-G and TC activity. The results obtained were as follows:
1) Metal ion solutions: TC activity decreased markedly in a ferric ion solution; PC-G did so in a cupric solution.
2) Albumin solutions: PG-G displayed recurrence in solutions of human or rat albumin, but not in solutions of egg albumin. TC presented no recurrence in any of the solutions.
3) Mixture of metal ions and human albumin: Both PC-G and TC showed recurrence in the mixture.
4) Differential absorption spectrum studies Changes were found in the differntial absorption spectrum of TC at 360 mμ and in that of PC-G at 255 mμ or 262 mμ in the presence of metal ions. The addition of human albumin reduced these changes. Assays of antibacterial activity under the same conditions revealed that the latter can almost parallel to the changes seen in the differential absorption spectrum.
The above mentioned results suggest that the recurrence of TC activity may be related to both metal ions and protein; while that of PC-G may be related to protein.