Do We Understand Protein Folding

In the opinion of a maximalist, the folding problem is the one of prediction if we knew the primary structme, could we in principle predict the tertiary one As we mentioned before, the latter question is a practical one. If the answer were yes , we would no longer need complicated and expensive X-ray and NMR analysis of proteins. Unfortunately, the ideal full prediction is far from being true despite impressive achievements in some cases. At present, we can guess the secondary structure with decent accuracy (i.e. a- and /3-segments), but predicting the tertiary structure remains elusive. In this sense, protein folding is definitely not resolved. 

But in terms of these fundamentals, we would dare to say that an important progress had been achieved over the last several years. Previously, at the time of Anfinsen, protein folding seemed a fundamental physics mystery. People could not imagine how it could be happening even in principle. Now, there is at least an overall understanding of the basic physics behind folding, as we tried to outline in the present chapter. There are lattice models, which are very much unlike proteins in many respects (too many and too obvious to list) — but which are like proteins in two most important aspects they have the same fundamental difficulties, such as Levinthal paradox, and they do fold. And we understand this model pretty well But, of course, the study continues in many directions... 

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