Self-assembly and crystallisation of proteins

This chiral liquid crystalline arrangement is not limited to structural proteins. Precholesteric and cholesteric mesophases have been found in DNA aqueous solutions [10]. 

It is likely that the other more complex hyperbolic mesophases are also to be found in chiral systems twisted grain boundary and blue phases (whose twist numbers are less than and greater than unity respectively, cf. section 4.14), are also prevalent in proteinaceous matter. (Note that a blue phase of DNA in water has recently been reported [11]). 

In this context, some comments on protein crystallisation can be made. The process of crystallisation can be viewed as one of self-assembly of the quaternary structure, although the constituent units now have a well-defined arrangement in space, in contrast to their less rigid shape in liquid crystalline mesophases. Indeed, twisted structures are very commonly found in globular protein crystals, which are reminiscent of the hyperbolic forms of micro- and mesoporous zeolites, described in Chapter 2. 

The similar dimensions of many globular proteins and novel mesoporous zeolites offer fascinating possibilities for bio-organic-inorganic composites. For example, the inorganic mesoporous alumino-silicates have been proposed as templates for protein crystallisation [12], Conversely, proteins could be used to template mesostructured inorganic materials. 

Brandon and J. Tooze, Introduction to Protein Structure . (1991), Garland Publishing Inc. London.. 

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