derives from O-phosphopantetheine-L-serine modified residue with a secondary neutral loss modified L-serine residue O-phosphopantetheine-L-serine with neutral loss of pantetheine -260.119476318359375 -260.350006103515625 166.99835205078125 167.05999755859375 C -11 H -20 N -2 O -3 P 0 S -1 C 3 H 6 N 1 O 5 P 1 Covalent modification of a peptide or protein amino acid O-phosphopantetheine-L-serine with secondary neutral loss of pantetheine resulting in O-phospho-L-serine. MOD:00159 MOD:01452 PSI-MOD Phosphoserine is generated and detected after the facile elimination of pantethiene from the phosphopantethiene tertiary phosphodiester. See MOD:01451 for alternate origin. artifact