Interaction of a novel platinum drug with bovine serum albumin: FTIR and UV-Vis spectroscopy analysis

Abstract

Platinum complexes have proven to be very effective in cancer treatment. However, severe side effects of these drugs have lead scientists to pursue new platinum complex derivatives. A novel blue platinum compound, called Platinum-Blue (Pt-Blue), is one of the promising candidate platinum compounds to be used for tumor treatment. In this study, the interaction of Pt-Blue with bovine serum albumin (BSA) has been investigated using UV-Vis and FTIR spectroscopy. One of the findings is that the drug-protein interaction type depends on the drug concentration. Though Pt-Blue is attached to the surface of BSA at high concentrations, it interacts with a hydrophobic region of the protein at low concentrations with a binding constant of 1.93 x 10(5) M-1. Spectroscopic results indicate the hydrophobic docking position to be around Trp 213 in domain II, which is surrounded by a number of Asp and Glu. During this interaction, helices such as helix-10, helix-18, helix-19 and helix-24 change orientation and/or partially unfold to make room for the compound. Binding constants at high and low concentrations of Pt-Blue are determined using UV-Vis spectroscopy, which are found to be comparable to cisplatin. FTIR spectroscopy also reveals that the interaction between Pt-Blue and BSA is noncovalent, which makes the candidate drug favorable because it is available for DNA binding while being carried by albumin.