Sodium cyanoborodeuteride

Hexadecyltrimethylammonium chloride (≥98%, CTAC), tetraethyl orthosilicate (98%, TEOS), 1,6-diisocyanatohexane (≥99.0%), tridecane (≥99%), ammonium hydroxide solution (28 wt%, NH₃·H₂O), ammonium fluoride (≥98%, NH₄F), 3- aminopropyltriethoxysilane (99%, APS), formaldehyde (37 wt% in water), sodium cyanoborohydride (NaBH₃CN), sodium cyanoborodeuteride (NaBD₃CN), trypsin (from bovine pancreas), protease inhibitor cocktail, formic acid (FA), urea, trifluoroacetic acid (TFA), dithiothreitol (DTT), iodoacetamide (IAA), and ammonium acetate were purchased from Sigma-Aldrich (St. Louis, MO, USA). Phosphatase inhibitor cocktail was ordered from Thermo Fisher Scientific (Rockford, USA). ¹³C-D₂-formaldehyde was purchased from Cambridge Isotope Laboratories, Inc. (Andover, USA). Dry pyridine was provided by Aladdin (99.8%, Shanghai, China). Toluene and chloroform (≥99.0%) were bought from Kaixin (Tianjin, China), and toluene was purified by refluxing (110 °C) over sodium and distilling (136 °C). Acetone (≥99.5%) and ethanol (≥99.8%) were obtained from Kermel (Tianjin, China). Acetonitrile (≥99.9%, ACN) was purchased from Merck (Darmstadt, Germany). Deionized water was used throughout the experiments (Millipore, Milford, MA, USA). Other reagents were all analytical grade. All the standard non-phosphorylated peptides were purchased from ChinaPeptides (Shanghai, China).