The electrochemically induced conformational transition of disulfides in bovine serum albumin studied by thin layer circular dichroism spectroelectrochemistry

The conformational transition of disulfides in bovine serum albumin (BSA) i nduced by electrochemical redox reaction of disulfides were monitored by in -situ circular dichroism (CD) spectroelectrochemistry, with a long optical path thin layer cell and analyzed by a singular value decomposition least s quare (SVDLS) method. Electrochemical reduction of disulfides drives the le ft-handed conformation of disulfides changed into the right-handed. At open circuit, eight of the 17 disulfides were of left-handed conformation. Four of the 17 disulfides took part in the electrochemical reduction with an EC mechanism. Only one-fourth of the reduced disulfides returned to left-hand ed conformation in the re-oxidation process. Some parameters of the electro chemical reduction process, i.e. the number of electrons transferred and el ectron transfer coefficient, n=8, alphan=0.15, apparent formal potential, E -1(0') = -0.65(+/-0.01) V, standard heterogeneous electron transfer rate co nstant, k(1)(0) = (2.84 +/- 0.14)x 10(-5) cm s(-1) and chemical reaction eq uilibrium constant, K-c=(5.13 +/- 0.12) x 10(-2), were also obtained by dou ble logarithmic analysis based on the near-UV absorption spectra with appli ed potentials. (C) 2001 Elsevier Science B.V. All rights reserved.