Electrochemical studies of the interaction of tetraphenylporphyrin tetrasulfonate (TPPS) with albumin

An electrochemical investigation of the interaction of TPPS with BSA on a Hg electrode is reported for the first time. The addition of BSA to TPPS solution results in a decrease of both the reduction and the oxidation current with no change of the peak potentials. In presence of BSA, no new peaks appear, and the standard rate constant k _s is not significantly changed. The reaction of TPPS with BSA yields a kind of supramolecular complex TPPS-BSA, which is electrochemically non-active. The equilibrium constant for the complex has been calculated. The decrease of the peak current can be used to determine BSA concentrations. Received: 2 August 1998 / Revised: 21 September 1998 / Accepted: 24 September 1998