Dl dithiothreitol

Trypsin, endoprotease Lysine-C (LysC), whole cell yeast protein extract from Saccharomyces cerevisiae, whole cell protein extract from human K562 cells, and DL-dithiothreitol (DTT) were obtained from Promega in Madison, WI. MS-grade Pierce LysN protease (LysN) was obtained from Thermo Fisher in Rockford, IL. Bovine serum albumin (BSA), bradykinin, poly-DL-alanine, iodoacetamide (IAA), and trifluoroacetic acid (TFA) were purchased from Sigma Aldrich in St. Louis, MO. Optima grade water, acetonitrile (ACN), formic acid (FA), and acetic acid (HAc) were purchased from Fisher Scientific in Pittsburg, PA.

Chemicals were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA), unless stated otherwise. Carbo-free blocking solution was purchased from Vector Laboratory (Burlingame, CA, USA). SuperSignal West Pico Chemiluminescent Substrate was purchased from Thermo Scientific (Rockford, IL, USA). Precast gel (4–20%) and Precision Plus Protein Standard Kaleidoscope Pre-stained protein markers were purchased from Bio-Rad (Hercules, CA, USA). Percoll was purchased from Pharmacia (Piscataway, NJ, USA). NP-40 was purchased from Calbiochem EMD Millipore (Billerica, MA, USA). SimplyBlue SafeStain was purchased from Life Technologies (Carlsbad, CA, USA). The BCA assay kit was purchased from Thermo Scientific. Biotinylated glycans were obtained from Lectinity (Moscow, Russia). ACS grade methanol (MeOH), ACS grade acetonitrile (ACN), Optima LC-MS grade ACN, Optima LC-MS grade water and ammonium bicarbonate were purchased from Fisher Scientific (Pittsburgh, PA, USA). Deionized water (18.2 MΩ cm) was prepared with a Milli-Q Millipore system. Formic acid (≥98%) was obtained from Fluka (Buchs, Switzerland). DL-Dithiothreitol (DTT), Protease-Max surfactant and sequencing-grade modified trypsin were purchased from Promega (Madison, WI, USA). Recombinant lactadherin protein was purchased from R&D Systems (Minneapolis, MN, USA; product 2805-MF/CF).