Ldqwlc cam ek

α-LA standard (≥85% purity) from bovine milk, modified porcine trypsin (proteomics grade), iodoacetamide, dithioerythritol (DTE), and triethylammonium bicarbonate (TEAB) buffer (1M) were obtained from Sigma-Aldrich Inc. (Steinheim, Germany). LC-MS grade acetonitrile (ACN) and formic acid (FA) were obtained from Merck (Damstadt, Germany) and Honeywell Fluka (Roskilde, Denmark), respectively. β-CN standard (>90% purity) was purified from bovine milk according to Petrat-Melin et al. (2015) (link). The purity relative to total protein was determined by LC/ESI-MS. The peptide standards (LDQWLC[CAM]EK, VGINYWLAHK, VLPVPQK and AVPYPQR) and isotope labelled peptides as internal standards (ISTD) (LDQWLC[CAM]EK∗, VGINYWLAHK∗, VLPVPQK∗ and AVPYPQR∗ with the asterisk representing isotope labelled C13 and N15 at K or R) were purchased from Thermo Fisher Scientific (Biopolymers, Ulm, Germany) as AQUA Ultimate. Purity of these peptides was above 97% as in the certificates.