26.12.2014 Views

Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

I. Introduction<br />

665<br />

The stability <strong>of</strong> calcium complexes <strong>of</strong> ethylenediamine tetraacetic<br />

acid (EDTA) and its homologues with increasing<br />

number <strong>of</strong> C atoms in the bridge between N atoms is as<br />

follows:<br />

Although a further discussion <strong>of</strong> ligand basicity and steric<br />

effects is beyond the scope <strong>of</strong> this chapter, knowledge<br />

<strong>of</strong> the following relationship can be useful where various<br />

coordinating groups are compared in order <strong>of</strong> decreasing<br />

affinity for given metal ions:<br />

N Atom in Bridge Carbon Log K a<br />

2 5 10.5<br />

3 6 7.1<br />

4 7 5.2<br />

5 8 4.6<br />

Such complexes are called chelates. Note that the stability<br />

also increases as the number <strong>of</strong> rings increases:<br />

Ligand Number <strong>of</strong> Rings Log K a<br />

H 2 NCH 2 COOH 1 5.2<br />

CH 2 COOH<br />

NHCH 2 COOH 2 7.0<br />

CH 2 COOH<br />

NCH 2 COOH<br />

CH 2 COOH 3 10.6<br />

CCO<br />

> NH2<br />

> NN><br />

N<br />

> COO<br />

> O>><br />

CO<br />

Enolates > Amino > Azo > Ring N > Carboxylate<br />

> Ether >> Carbonyl<br />

These relationships are important to the types and<br />

shapes <strong>of</strong> complexes that metal ions form, their stabilities,<br />

and their redox potentials.<br />

C . Biological Perspectives<br />

1 . Trace Elements as Essential Components in Evolution<br />

and Animal Diversity<br />

A reasonable question to ask is why are certain elements<br />

more nutritionally important than others From an evolutionary<br />

perspective, relative abundance and, in many cases,<br />

the ability to form complexes with catalytic (redox) potential<br />

are among the most important reasons. Figure 22-1<br />

shows the distribution <strong>of</strong> elements in seawater, bacteria,<br />

fungi, plants, and animals ( Banin and Navrot, 1975 ). That<br />

3.6<br />

Bacteria<br />

G<br />

N<br />

3.6<br />

Fungi<br />

G N<br />

0<br />

12<br />

24<br />

Log<br />

36<br />

Enrichment<br />

Factor 48<br />

60<br />

72<br />

84<br />

K<br />

Na<br />

Sea water<br />

CuMg<br />

Sr<br />

Ca<br />

Cd<br />

Zn<br />

Cu<br />

Mg<br />

Mn<br />

Cr<br />

Fa<br />

Cd<br />

Si<br />

B<br />

Ma<br />

Mo<br />

P<br />

S<br />

C<br />

N<br />

Log<br />

Enrichment<br />

Factor<br />

1.2<br />

0<br />

1.2<br />

3.6<br />

3.6<br />

K<br />

Na<br />

0.0<br />

Cu<br />

Zn Mg<br />

Ca<br />

Mn<br />

Plants<br />

Mo<br />

Fa AJ Si<br />

B<br />

P<br />

S<br />

0.5 1.0 1.5<br />

G<br />

N<br />

1.2<br />

0<br />

1.2<br />

3.6<br />

3.6<br />

K<br />

Na<br />

0.0<br />

Cd<br />

Zn<br />

Sr<br />

Cu<br />

Ca<br />

Ma<br />

<strong>Animals</strong><br />

Mg<br />

Ni Cr<br />

Fa<br />

Mo<br />

B<br />

Si<br />

AJ<br />

P<br />

S<br />

0.5 1.0 1.5<br />

G<br />

N<br />

0.0 0.5 1.0 1.5<br />

Log ionic potential<br />

Log<br />

Enrichment<br />

Factor<br />

1.2<br />

0<br />

1.2<br />

3.6<br />

S<br />

Cd<br />

B<br />

P<br />

K Zn Mo<br />

Ca<br />

Mg<br />

Na Sr Mn Cu<br />

Ca Ni<br />

Si<br />

Fa Cr<br />

AJ<br />

Co<br />

1.2<br />

0<br />

1.2<br />

3.6<br />

K<br />

Za<br />

P<br />

Zn<br />

Ca<br />

Mo<br />

Cd<br />

B<br />

Sr Md<br />

Ni Si<br />

Cu Fa<br />

Cr<br />

Mn Ag<br />

S<br />

0.0 0.5 1.0 1.5<br />

Log ionic potential<br />

0.0 0.5 1.0 1.5<br />

Log ionic potential<br />

FIGURE 22-1 Distribution <strong>of</strong> elements in seawater, bacteria, fungi, plants, and animals relative to the earth’s crust plotted as a function <strong>of</strong> the ionic<br />

potential (see text).

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!