Evaluation of OS environment

The occluded surface area for each residue is compared to the distribution of occluded surface areas for that type of amino acid in a data set of high resolution structures. The output is found in the file, prot.eval as shown below.

The two important parameters here are Ri and Psr. A plot of Ri tells you which residues are in unusual environments. And Psr should be between 0.60 and 0.74 or your structure is probably wrong.

...
Sw:           26.87    THR  316
St:           90.10    THR  316
Ri:            0.30    THR  316
Sw:           52.73    PRO  317
St:           92.00    PRO  317
Ri:            0.57    PRO  317
    Total_Res:      317 
    Pw:        20144.56 
    Pi:        30304.49 
    Psr:           0.66 

where,

Sw is a weighted surface area of the residue. This parameter is a function of both the occluded surface area of the residue and the distribution of occluded surface areas found in a data set of high resolution structures.

St is the total surface area for that residue type.

Ri is a weighted parameter describing how "usual" the occluded surface environment is:

Below a value of 0.2 indicates that the residue is in a highly unusual environment.

A value of 1.0 indicates that the residue is in a completely average environment for that residue type.

Total_Res is the total number of residues

Pw is the weighted surface area of the whole protein

Pi is the ideal weighted surface area of a protein with the same amino acid composition.

Psr is the normalized protein surface ratio. A value between 0.60 - 0.74 is found for properly folded proteins. If your structure has a Psr value outside of this range it is probably wrong.