The interaction between transplatin and urease was studied by microcalorimetry, DSC, circular dichroism (CD) spectrum and fluorescence spectrum. Transplatin can render urease inactive as is indicated by the experimental results of microcalorimetry. Thermal denaturation experiments of urease by DSC show that transplatin generally reduces urease thermal stability since urease T-m decreases dramatically. From the features of urease CD and fluorescence spectra, transplatin leads to urease conformational change at lower concentrations than in case of cisplatin. The interaction of transplatin with urease is stronger than that of cisplatin and the binding site of urease with transplatin may be different from that with cisplatin.