[BiO BB] Ramachandran plot.

Boris Steipe boris.steipe at utoronto.ca
Thu Mar 30 13:14:55 EST 2006

This is not misclassification: helices and strands have >>repeating<<  
residues with certain (phi,psi) values. The Ramachandran plot shows  
you a value for >>single<< residues. To classify a structural segment  
as belonging to a certain type you need more information than  
individual (phi,psi) values.


On 30 Mar 2006, at 10:57, Vivek Philip wrote:

> Hi,
>   While analyzing the plot of phi and psi angles on the  
> Ramachandran plot, we found out that there was a lot of overlap  
> between the alpha-helix and beta-sheet regions. By this we mean  
> that just based on the phi and psi angles alpha helices are meant  
> to be both negative, while for beta sheets phi angles take negative  
> values and psi positive. The results we used for generating these  
> plots were obtained from STRIDE and DSSP for top 500 high  
> resolution pdb structures.
>   Does anyone have an idea as to what the reason for such an  
> overlap could be? Moreover on further analysis we did see a lot of  
> misclassification particularly related to the pi-helix region (Only  
> about 38% of the residues were classified correctly).We are talking  
> about approximately 40% overlap between the two regions.
>   Any feedback on this would be greatly appreciated.
>   Thank you,
> Vivek
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