LACS

Linear analysis of chemical shift (LACS) provides an independent means for absolute referencing of protein chemical shifts.  In the contest of protein structure determination chemical shifts (CS) play a key role as reporters of secondary structure.  Backbone CS-derived dihedral angles can be obtained through programs such as TALOS+ and others are used as constraints in the structure determination process, backbone shift set (CA, CB, CO, HN, N, HA) are also used in the molecular fragment selection (MFR) for CS-Rosetta structure prediction protocol.  Any use of chemical shift for secondary structure inference requires the correct referencing.