Ez link nhs peg4 biotin 21363

Crude amine (∼104 µmol, 1 eq) was dissolved in DMF (2 mL), to which was added NHS-PEG4-Biotin (73 mg, 125 µmol, 1.2 eq, Thermo Scientific EZ-Link NHS-PEG4-Biotin—21363) and Hünig's base (55 µL, 312 µmol, 3 eq). The reaction was monitored by LC–MS analysis and was adjudged complete after 2 h. The reaction mixture was directly purified by semi-preparative HPLC (10–90% MeCN in H₂O over a 35-min gradient at 4 mL min⁻¹ using Phenomenex Luna, 5µ, C18, 100 Å column). The product fractions were combined and freeze dried to give TDB3 (10 mg, 10% yield over four steps) as a red/orange powder. The corresponding m/z as detected by LRMS via electrospray ionization is the following: m/z (ES+) 1,080 [M + H]⁺, m/z (ES−) 1,078 [M − H]⁻.

Crude amine (∼48 µmol, 1 eq) was dissolved in DMF (2 mL), to which was added NHS-PEG4-Biotin (53 mg, 53 µmol, 1.1 eq, Thermo Scientific EZ-Link NHS-PEG4-Biotin—21363) and Hünig's base (18 µL, 105 µmol, 2.2 eq). The reaction was monitored by LC–MS analysis and was adjudged complete after 1 h. The reaction mixture was directly purified by semipreparative HPLC (10–90% MeCN in H₂O over a 35-min gradient at 4 mL min⁻¹ using Phenomenex Luna, 5µ, C18, 100 Å column). The product fractions were combined and freeze dried to give TDB2 (7 mg, 15% yield over three steps) as a red/orange powder. The corresponding m/z as detected by LRMS via electrospray ionization is the following: m/z (ES+) 986 [M + H]⁺, m/z (ES−) 984 [M − H]⁻.