Pathogenicity islands are a characteristic feature of pathogenic bacteria genomes.These are large regions (10 to 200 kb) that are present in the genomes of pathogenic species but absent from the genomes of nonpathogenic variants of the same or related species. 

#Id: 7701

#Unit 1. Structure and Function of Biomolecules

                                                                  Omega loop

Beginning and end of the loop come together

The shape appears similar to Greek Capital Omega

Compact Globular structure

No regular repeating pattern of hydrogen bonds

Side chains pack into the center of the loop

Omega loops have specific functions like

Omega loop from two proteins interact with each other to form dimers

Phosphate binding loop of nucleotide proteins

#Id: 7702

#Unit 1. Structure and Function of Biomolecules

                                                             Omega loop

#Id: 7704

#Unit 1. Structure and Function of Biomolecules

                                                           Loops and Turn

Small loops with regular hydrogen bond pattern and specific dihedral angles are termed as turns

#Id: 7705

#Unit 1. Structure and Function of Biomolecules

                                                               β-turns

Most common turns, also termed as ẞ-bends, tight turns, reverse turns, generally connects

β-sheets.

The conformation of i+1 and i+2 are crucial and on the basis of this, they are classified

Consists of 4 amino acids, generally termed as i, i + 1 , i + 2 and i + 3

H-bond is seen between i and i+3 (First and Fourth residue)

#Id: 7706

#Unit 1. Structure and Function of Biomolecules

                                                                                                Type I β turn

#Id: 7707

#Unit 1. Structure and Function of Biomolecules

H bonding i-i+3, i+1 in BS while i+2 in below LHH which virtually not allowed region

for most of amino acid except Gly that is why Gly is most conserved in type II B turns

                                                                Type II β turn