Macromolecules in biological systems

While the number of possible conformers of a macromolecule is practically unlimited, it is a common observation that macromolecules in biological systems occupy only an extremely limited portion of the conformational hyperspace open to them. As a result, they exhibit well-defined shapes which confer upon them the emergent property of functionality (see Section 2.3.3). 

II. METAL-CONTAINING MACROMOLECULES IN BIOLOGICAL SYSTEMS A. Metal Complexes In Living Systems... 

Interactions between macromolecules (protems, lipids, DNA,.. . ) or biological structures (e.g. membranes) are considerably more complex than the interactions described m the two preceding paragraphs. The sum of all biological mteractions at the molecular level is the basis of the complex mechanisms of life. In addition to computer simulations, direct force measurements [98], especially the surface forces apparatus, represent an invaluable tool to help understand the molecular interactions in biological systems. 

Enzymes are remarkable molecular devices that determine the pattern of chemical transformations in biological systems. The most striking characteristics of enzymes are their catalytic power and specificity. As a class of macromolecules, they are highly effective in catalyzing diverse chemical reactions because of their ability to specifically bind to a substrate and their ability to accelerate reactions by several orders of magnitude. Applying enzymes or organisms in... 

The observation of biological macromolecules in cellular systems is based on labeling schemes that enable the selective identification of these macro-... 

Molecular recognition in biological systems (active sites on the surfaces of macromolecule, antibody-antigen) and biological sensors (enzyme activity, biosensors). 

The mechanisms of protection by these compounds have been evaluated for irradiated polymers. Many so-called protectors contain sulfhy-dryl groups and appear to operate by replacing or capturing the hydrogen atom lost by irradiating the macromolecule. It appears most reasonable to assume mat the same mechanism often occurs in biological systems. 

What makes synthetic organic chemists the most qualified individual to assume the leadership role in the design of safer chemicals is their ability to understand chemical reactivity at the molecular level. The basis of a chemical s commercial utility, and also its toxicity and any adverse environmental impact that it will cause, is ultimately based on how its molecules will interact with the molecules of other chemicals. These other molecules include those involved with the intended use of the commercial chemical, in addition to those found in biological systems, such as macromolecules in humans, or molecules or atoms found in the environment. 

A large number of investigations of the mechanism of electron transfer reactions of macromolecule-metal complexes in biological systems has been reported. These investigations were concerned with not only natural metalloenzymes such as cytochromes, ferredoxin, blue coppers, oxygenase, peroxidase, catalase, hemoglobin, and ruberodoxin, but also modified metalloenzymes 47). 

It may be said that in biological systems specific interactions between macromolecules are quite important and that the various functions realized in... 

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