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What is FRAG?

A FRAG is one of the pre-calculated SUBSTRUCTURE types, and is defined as a fragment obtained when all rotatable bonds are cut. A rotatable bond is defined in the following way: only a single bond (saturated bond) that is not included in any ring substructure can be rotated. Amide bonds are not rotatable as they are known to have an energy barrier that prevents rotation. Two cases that have not yet been considered are where steric hindrance prevents rotation, and where an enzymic reaction helps rotation (such as occurs with cis-trans-isomerases). A bond consisting of one hydrogen atom and one non-hydrogen atom is also excluded. FRAG entries can be searched using Substructure Search option.


BiSSCat Structure Search option

The BiSSCat Structure Search option can be used to look up compounds, functional groups, and substructures based on structural information or physicochemical properties.

BiSSCat v1.07.31
Developed by Masaaki Kotera, Department of Biochemistry, Trinity College Dublin.
Science Foundation of Ireland is gratefully acknowledged.