Background: The metal ions play a vital role in a large number of widely differing
biological processes. Some of these processes are quite specific in their metal ion requirements.
In that only certain metal ions, in specific oxidation states, can full fill the necessary
catalytic or structural requirement, while other processes are much less specific.
Objective: In this paper we report the binding of Mn (II), Ni (II) and Co (II) with albumin
are reported employing spectrophotometric and pH metric method. In order to distinguish
between ionic and colloidal linking, the binding of metal by using pH metric and viscometric
methods and the result are discussed in terms of electrovalent and coordinate bonding.
Methods: The binding of Ni+2, Co+2 and Mn+2 ions have been studied with egg protein at
different pH values and temperatures by the spectrometric technique.
Results: The binding data were found to be pH and temperature dependent. The intrinsic
association constants (k) and the number of binding sites (n) were calculated from
Scatchard plots and found to be at the maximum at lower pH and at lower temperatures.
Therefore, a lower temperature and lower pH offered more sites in the protein molecule for
interaction with these metal ions. Statistical effects seem to be more significant at lower
Ni+2, Co+2 and Mn+2 ions concentrations, while at higher concentrations electrostatic effects
and heterogeneity of sites are more significant.
Conclusion: The pH metric as well as viscometric data provided sufficient evidence about
the linking of cobalt, nickel and manganese ions with the nitrogen groups of albumin.
From the nature and height of curves in the three cases it may be concluded that nickel ions
bound strongly while the cobalt ions bound weakly.