Most
chemical or biological molecules may be in solution, for example in water, or
in the solid state, for example as a crystal or in the form of a powder. Molecules may be small (such as naphthalene,
nicotinic acid, sodium chloride etc.), large (such as proteins or nucleic acids)
and very large (such as viruses). In a
very simplistic explanation, the three-dimensional structure of a molecule
describes the relative location of each atom of the molecule in relation to the
other atoms in the molecule, as well as the folding pattern of the molecule
itself. Further, these structures may
also describe how the particular molecule is packed in three-dimensional space
and what intra-molecular or inter-molecular interactions are responsible for its
mechanism of action. This is
particularly important for studying structure-function relationships as an aid
to drug design.
Several
methods are available for elucidation of the three-dimensional structures of
molecules of various sizes, such as X-ray Diffraction, Nuclear Magnetic
Resonance and several others.
In an essay of approximately four pages
(typed double-spaced, font size 12) briefly discuss the various methods for
structure determination along with their advantages and disadvantages. Please do not fill up your essay with
equations or very detailed descriptions of the procedures involved. Basic principles of each method should be
discussed, along with its suitability for a particular class of molecules (for
example small or large, organic or biological, in powder form or in the
crystalline state or in solution and other such distinctions). Some examples
of momentous discoveries stemming from such methods will be particularly
relevant. Feel free to add a short paragraph
of your own comments.
The page limit is a suggestion and may
be exceeded if you have more to offer. The
essay will be graded based on its cogency, relevance to the material requested,
depth of research, pertinent examples, comments and general structure.
