Biological macro molecules

Volume 323. Energetics of Biological Macro molecules (Part C)... 

As mentioned earlier, biological systems have developed optimized strategies to design materials with elaborate nanostructures [6]. A straightforward approach to obtaining nanoparticles with controlled size and organization should therefore rely on so-called biomimetic syntheses where one aims to reproduce in vitro the natural processes of biomineralization. In this context, a first possibility is to extract and analyze the biological (macro)-molecules that are involved in these processes and to use them as templates for the formation of the same materials. Such an approach has been widely developed for calcium carbonate biomimetic synthesis [13]. In the case of oxide nanomaterials, the most studied system so far is the silica shell formed by diatoms [14]. 

Over the last two decades mass spectrometry has become one of the central techniques in analytical chemistry, and the analysis of biological (macro)molecules in particular. Its importance is now comparable to that of the more traditional electrophoresis and liquid separations techniques, and it is often used in conjunction with them as so-called hyphenated techniques, such as LC-MS. 

Tombs MP, Peacocke AR. The osmotic pressure of biological macro-molecules. Oxford Clarendon Press 1974. 

The distance scale on which FRET occurs makes the technique very attractive in the life sciences because it corresponds well to relevant distances in biology for example, the distance between base pairs in double-stranded DNA is 0.3 nm. The potential of FRET to reveal proximity in biological macro molecules was already pointed out in 1967 by Stryer and Haugland in their article Energy Transfer A Spectroscopic Ruler [98]. In their pioneering experiment, they labeled poly-pro-line peptides of different lengths at both ends and demonstrated the R dependence of the energy-transfer efficiency. Today, FRET is a weU-established spectroscopic technique [57, 58]. For a review, see the article by Selvin [99]. 

Wuthrich, K. 2002. NMR studies of structure and function of biological macro-molecules. Nobel Lecture 235-267. 

C. R. Cantor and P. R. Schimmel, Biophysical chemistry, part I The conformation of biological macro-molecules, part III The behavior of biological macromolecules,... 

Hydrophobic interaction chromatography (HIC) separates biological macro molecules according to the hydrophobic groups on their surface. It shows many parallels to lEC HIC is... 

In general, the chromophores found typically in solutes, such as proteins, nucleic acids, carbohydrates and lipids (i.e. our biological macro molecules or macromolecular assemblies). 

In contrast with proteins and nucleic acids, carbohydrates and lipids possess few substantial inherent chromophores and so neither class of biological macro molecule has a particularly rich or useful UV-visible spectroscopic behaviour. Therefore, we shall focus the next section on structural versus functional information available from the UV-visible spectroscopy of proteins and nucleic acids only. 

Derivation of biological macro molecular structure by NMR spectroscopy involves the application of a variety of multidimensional NMR spectroscopy experiments, many of which are beyond the scope of this chapter. Nevertheless, there are some basic principles and ideas that the chemical biology reader should be aware of, which we shall attempt to cover. These basic principles and ideas pull very heavily on the discussion in Main Sections 5.3 and 5.4 above. In brief, the structural characterisation of a biological macro molecule by NMR spectroscopy draws upon a similar approach in every single case. The key objectives are the following. 

Practical realisation of vitreous ice embedded samples of individual biological macromolecules is usually achieved with a holey carbon grid (Figure 6.21), which is a thin carbon-based support him (50-200 nm in dimensions) perforated with holes and mounted on a standard electron microscope sample grid. An aqueous sample of a biological macro molecule... 

Water hydration and counter-ion solvation of biological macro molecules considerably alter the translational and rotational dynamics ofbiological macromolecules. The effect can be correlated with a number of different solution properties of a given biological macromolecule such as the hydrated volume Vh- The term Vh is given by... 

Unfortunately, a uniformly hydrated sphere provides a rather poor approximation of many other biological macro molecules in solution. Instead, an oblate ellipsoid or a prolate ellipsoid give a much closer approximation to the shape of many biological macro molecules in solution that are not spherical but are compact, globular or irregular rigid bodies (Figure 7.11) In this event, there is a further need to modify the equations that define translational and rotational friction forces. Hence Equation (7.5) becomes... 

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