Collect. Czech. Chem. Commun. 1980, 45, 669-678

Effect of temperature on catalytic hydrogen currents of native and modified bovine serum albumin

Izaak Maurits Kolthoff and S. Kihara

Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 554 55, USA


The effect of temperature has been studied on three different catalytic hydrogen currents observed voltammetrically and on two of them polarographically with serum albumin and modified products of albumin adsorbed on mercury. The so-called "active cobalt catalytic current", ic and "presodium current", ips increase with increasing temperature. The temperature effect on the so-called Brdi_ka currents. i1 and i2 was found to be quite different from that on ic or ips. In ammoniacal buffer (pH = 9.3) in the presence of cobalt(III) or (II) i1 has been found virtually the same at temperature between 4° and 40°C, whereas i2 greatly decreases with increasing temperature. Evidence has been presented that in the presence of Co(III) or Co(II) and at 4°C all disulfide groups in the protein used are reduced to sulfhydryl at potentials at which i1 and i2 are observed. It has been concluded that the ligands of the protein which complex with Co(III) or Co(II) or Co(0) are different at potentials at which i1 is observed than at which i2 is observed. In order to account for the abnormal temperature effect on i2 it has been proposed that the area of the section of protein which is the seat of i2 is being detached from the surface with increasing temperature and that this process is reversible.