Research Article

Comparison of Heavy Labeled (SIL) Peptide versus SILAC Protein Internal Standards for LC-MS/MS Quantification of Hepatic Drug Transporters

Table 1

MRM parameters of peptide selected for targeted analysis of OATP1B1, OATP1B3, OATP2B1, and P-gp. The labeled amino acid in the internal standard is shown in bold and italic.

Transporter PeptideParent ion Product ionsFragmentor (V)Collision energy (eV)
12

OATP1B1NVTGFFQSFK587.9961.4860.512513
NVTGFFQSFK591.9969.5868.512514

OATP1B3NVTGFFQSLK570.8927.5826.313014
NVTGFFQSLK574.8935.6834.313014

OATP2B1VLAVTDSPAR514.8816.4846.413013
VLAVTDSPAR519.9826.4856.412513

P-gpNTTGALTTR467.8618.3719.412512
NTTGALTTR472.8628.3729.512512

Isotopic purity of synthetic SIL peptides was 100%. SILAC protein labeling was achieved up to 95.8% (OATP1B1), 98.1% (OATP1B3), 97.2% (OATP2B1), and 98.2% (P-gp).