Aperiodic Crystal or Equilibrated Glass

At first glance, self-organization seems very straightforward. Suppose we have a certain chain with a fixed sequence of monomers. In the right sort of circumstances, left on its own, it wiU always roU up into a coil in exactly the same way. We take up the same thing every time, and obtain the same outcome is this really so strange Yet this phenomenon is unique, it is completely unlike anything else in physics. Let s discuss this problem in more detail. 

Erwin Schrodinger (1887-1961), one of the founders of quantum mechanics, in his famous essay [37] on What is Life based on lectures delivered in Dublin in 1943, at the height of the war (by the way, in our opinion — a must reading for anyone interested in biological physics), coined the special term aperiodic crystal. This is intentionally an oxymoron. Aperiodic cr3 tal is a crystal in the sense that every atom or 

as we also mentioned, protein globule consists of so diverse molecular groups, that their arrangement in space is inevitably very irregular. In this sense, a protein globule resembles so-called disordered systems, also known to physics, such as an amorphous solid or a glass. Alas, we shall see shortly that this analogy is very limited too. It does not go much deeper than the very fact of the lack of spatial periodicity. 

In fact, there is a remarkable, even though also limited, resemblance between a glass and the primary structure of biopolymers. Indeed, if we take a protein molecule and place it in the solution conditions when it is stable, then more or less spontaneous rearrangements of the primary structure 

the tertiary structure can rebuild itself just like a stable crystal, and is irregular in shape just like a amorphous glass — but the crystal is aperiodic, and the glass is equilibrated. 

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