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Structure validation

Dear Bill,

I have read with interest Gert Friend's letter concerning structure validation with the program WHAT_CHECK (Vol. 5, No. 4).

Your comment reminds me that in their paper on crystallization of macromolecules, Giegé & Ducruix (1992) show a figure describing the increase in the number of reported macromolecular crystal forms from 1940 to 1988. I have used that figure to predict three possible outcomes with respect to the future of macromolecular crystallography.

The first possibility would be a spike function, i.e. exponential increase, followed by a vertical drop. The number of macromolecular crystals grown (and hence the number of 3-D structures reported) would drop to 0 in the near future due to the solution of the macromolecular folding problem starting from sequence information alone, a very bleak prospect since we would be out of jobs soon;

The second possible function is a sigmoid, ascending to a plateau region. From the Giegé & Ducruix paper, we should be near the inflexion point. This means that macromolecular crystallographers will have less and less work in the next 45-50 years. We ourselves are fine, but should not breed new generations of macromolecular crystallographers;

The third possibility is an exponentially ascending function, with the number of crystal forms reported reaching infinity in an asymptotic manner. With an infinite number of crystal forms, whose 3-D structures must be determined, there will be an infinite number of crystallographers required to solve these structure and report their results. The known universe will be populated solely by crystallographers.

Perhaps this is what religions call the End of the World, with the rising of the dead (all crystallographers, of course), the coming of the chosen one (different names in different religions), the Last Judgment (i.e. the number of errors and anomalies in the reported structures) supervised by the Head Crystallographer (different names for different religions, YAHVE is the one that comes to my mind right now, other possibilities being OMEGA PIU etc).

Reference: R. Giegé, A. Ducruix, (1992), in "Crystallization of Nucleic Acids and Proteins, a Practical Approach' (A. Ducruix, R. Giegé, Eds.), IRL Press, Oxford, pp. 12.

I look forward to hear your views on this matter.

F.M.D. Vellieux, CEA CNRS, Grenoble, France

Dear Fred,

Option three sounds like heaven to me.