TYBSC SEMESTER V BIOINORGANIC CHEMISTRY

1. The role of Model systems
Most biochemical molecules are usually big and very complex structurally. It is advantageous to
synthesize and study, smaller and simpler models of biomolecules. These are called model systems
which can mimic the biological chemical process.
On these molecules-controlled experiments can be performed easily. These studies can be extended
to understand the activity and response of biomolecules.
In bioinorganic chemistry, the model systems of transition metals are studied with organic ligands
that could mimic biological chemical reactions.
It is difficult to find or develop suitable models.
Also, it can be dangerously misleading if over simplistic models are interpreted naively.
A model can give only a partial view of how the real system works.
However, with limitations, the model system approach can provide valuable information about
biological real systems.
The comprehensive knowledge of coordination chemistry is important in understanding the role of
metal ions in biological systems.
Fundamental principles and generalizations properties of metal complexes are valid whether the
metal is coordinated by some relatively simple set of man-made ligands or by a gigantic protein
molecule, where the coordinating groups are often carboxyl or aqua oxygen atoms, thiol sulfur
atoms, or amine nitrogen atoms.
The optical spectra, magnetic moments, and EPR spectra of transition metal ions are important tools
for study that can be applied to such models and real systems.
Thus, we have methods for checking the models against the real systems.
Throughout the discussion at the academic level, we refer to model systems that have played a role
in understanding real bioinorganic systems.
The model iron/metal-porphyrin compounds provide an understanding of hemoglobin, myoglobin,
cytochromes, enzyme P-450, hemerythrin, vitamin B12; iron-sulfur cluster compounds as models
for ferredoxins; and copper complexes/porphyrin serve as models for a variety of copper-containing
enzymes/hemocyanin.