PATTERNS OF LOOP REGIONS IN PROTEINS

The commonly occurring loop structures and their sequence patterns for the key hydrophobic, hydrophilic and glycine residues are described. There is a restricted number of the loop motifs consisting of three to six residues that occur most often and these small standard structures can be considered as elements of irregular regions. A short loop has, as a rule, conformation of one of the small standard structures and a longer loop can be represented as a combination of two or more small standard structures.