0 Members and 1 Guest are viewing this topic.
Beyond the constraints of life, protein tend to form both left and right handed helixes, in equal proportions.
Let us look a little deeper into the subcellular world down to the level of the protein molecules – the building blocks that make up the enzyme complexes responsible for the biochemical reactions. It has been known since the early work of Kauzmann (1959) and Tanford (1968) on the thermodynamics and kinetics of protein denaturation, that proteins are not very stable. In thermodynamic terms, the stabilities lie in the range 20 – 60 kJ/mol. However, H-bond energies are quoted also in the range 12 – 38 kJ/mol (Fersht, 1999). Comparing these figures, one is struck by their apparent incongruity – they mean that protein stability relies on a few H-bonds. It is even conceivable that some H-bonds are more stable than small proteins. For example, Finney (1982) gives the stability of lysozyme and ribonuclease as equivalent to 4 H-bonds each. One naturally asks, how can a molecule containing thousands of atoms be held together by a few H-bonds? I am not saying that these figures are wrong, but rather that another energetic mechanism for protein stability has to be found – one that has not been detected by classical methods.One is reminded here of the problem of protein folding. As I have pointed out elsewhere (Watterson, 1997), that problem also arises from applying classical theories, since they predict an average, not a unique fold. That these questions remain unsolved still today after 50 years of intense research effort, highlights a two-fold failing of statistical methods: firstly, they did not predict the existence of a stable folded state, and secondly, once given as an experimental fact, they cannot explain it.
The side groups are varied and each type will have their own potential. This will cause the backbone helix to fold.
Another related observation is the left handedness of protein in cells. Beyond the constraints of life, protein tend to form both left and right handed helixes, in equal proportions. This is like throwing a two sided dice, with heads and tails coming up with equal probability. But with life, heads; left, comes up thousands of time in a row. The odds of thousands of heads in a row, means the is no longer gambling, but has become a sure thing; loaded coin.