Immediate follow thru

Decided to spend the time blogging the theory of metal transport. If it gets too deep - well, mea culpa. If this makes sense - dr. lenny needs some active support to delve further down this trail.

Inorganic poisons based on metal centers tend to accumulate in biological systems. The chemistry of biology generally has one favored way of doing things and several more energetic back-up systems that can be used effectively, but not optimally. As heavy metals and other strongly charged large metal ions are introduced, they substitute for the ubiquitous first row transition metal ions. The latter are relatively small and comfortably divalent in the resting state.

These metal systems tend to be at the active sites of enzymes. The active site is like the control and guidence system of chemical biology - it makes sure the organic substrate gets into the next form, where it can be cyclically used in metabolism. Enzymes are protein based catalysts. They function by lowering the energy necessary for bond making or breaking. To remove the heavy metal, a chelator compound is necessary - one that has a specific affinity for the invader. Sometimes the metal forms a precipitate - a solid that appears in forms such as arterial plaque.

The charge difference in metal substitution is very important. When Al 3+ replaces Mg 2+ in a biomolecule, it also causes the loss of a Na +1 or K +1 ion. This creates a hole where there used to be an ion - because the net charge must remain balanced. It also creates free space. Molecules are crowded fairly close together and will move into any extra room where is can get confortable and be slack.

Sometimes the new ion inserted into the system is large enough to bridge connect chains and create bonds between side chains that would not otherwise be spacially close together. This creates a different folding pattern in the proteins tertiary and quartenary structures - the levels that dictate the atomic arrangement in space. These types of bonds shut down function, some refer to the modified enzymes as prions.

As far as scale - when a few cells pick up a toxin, the loss of function can be handled. But when multiple waves of metals accumulate, eventually the pathways shut down and survival of the organism comes into question. Remember, both the thermodynamics and the kinetics have to work to get things right.

This is a description of how metals work in biological systems. It might also offer an alternative explantion for prion type diseases and offer some constructive thought in the design of remediation techniques for chemically contaminated lands. By looking at hyper-accumulators in lichens, mosses, liverworts and fungi, we may be able to design ecological systems that stabilize and restore. Of course, nature does that with its time anyway.

Thanks for reading.