Protein has 3 levels of structure: Primary- at sequence level, Secondary- local arrangement of the polypeptide chain and tertiary - the three dimensional arrangement of a protein in space. There are 3 major elements of secondary structure of protein- helix, sheet and loops. Helix and sheet are considered to follow regular pattern in terms of dihedral angles while loops are irregular in nature. ProRegIn exploits the fact that loops are a mixture of helix-like and sheet-like dihedral values and to some extent follow the regular pattern.

ProRegIn classifies all 20 amino acids in a protein into regular and irregular category for both phi and psi. It can be used to separate improbable structures from native-like probable structures. ProRegIn is currently used as one of the filters in Bhageerath methodology.

Instructions to use tool
1) Upload a pdb file (Upload Protein with one chain only) and Click 'Submit' button.
2) Regularity Index for a given protein will be shown in the form of table.