26
such a couple,
trical field,
(5) rate of diffusion,
(6) mobility in an elec-
(7) the configuration and stability of the metal
hydrates in solution, and (8) the configuration and stability
of coordination complexes of the metal ion with polar substances
other than water
(i.e.
proteins).
The characteristics of the
coordination complexes of metals with water and other polar
molecules are a reflection of the electronic configuration of
the metallic ion and the coordinated groups.
Ease of replace~
ment of a coordinated group by some other molecule will be
determined by the energies and entropies of complex formation.
The tendency of mucosubstances to form ionic complexes
with heavy metals has been considered by Kent and Whitehouse
(1955) in their work on the biochemistry of the amino sugars.
Mucosubstances,
formed by the association of the major groups
of biopolymers - proteins, polysaccharides and lipoids - are
common in the animal kingdom in which they function variously
as lubricants,
protective coatings and mechanical supports.
Although rare in the plant world, the amino-sugars of animal
mucosubstances are closely paralleled by the sulfated polysaccharides of algae in their ion-binding properties.
Both
cementing and lubricating mucosubstances display differences
in cationic binding, and in selectively binding certain cations
may directly influence the metabolism of metal salts.
In