Lct premier time of flight mass spectrometer

All starting materials were commercially procured and were used without further purification, unless specified. Reaction solvents were purifid by passage through alumina columns on a purifiation system manufactured by Innovative Technology (Newburyport, MA). NMR spectra were obtained on Varian NMR systems, operating at 400 MHz or 500 MHz for ¹H acquisitions and at 126 MHz for ¹³C acquisitions. LCMS analysis was performed using a Waters Alliance reverse phase HPLC (columns Waters SunFire C18 4.6×50mm, 3.5μm or Waters SunFire C8 4.6×50mm, 3.5 μm), with single-wavelength UV–visible detector and LCT Premier time-of-flight mass spectrometer (electrospray ionization) or Waters Micromass ZQ detector (electrospray ionization). All final compounds were purified by preparative reverse phase HPLC (columns Waters Symmetry RP8 30 × 50 mm, 5 μm column or OBD RP18 30 × 50 mm, 5 μm), with a single-wavelength UV–visible detector and Waters Micromass ZQ (electrospray ionization). For further details regarding preparative HPLC and LCMS protocols, see Supporting Information. All final compounds have purities greater than 95% based upon LC/MS.

Mass data for CTD-labeled HIV-1 CA were obtained with a Waters LCT Premier time-of-flight mass spectrometer, operating in positive ion mode and using electrospray ionization. Sample introduction was via a Thermo Proswift RP-4H monolithic column (1 mm inner diameter, 50 mm length), using a 100 μl/min flow rate and a solvent gradient from 100% H₂O to 80% methanol/20% acetonitrile (with 0.1% trifluoroacetic acid and 0.2% formic acid) in 9 min. The multi-charged m/z spectrum was deconvolved using the MaxEnt I program. Mass data for NTD-labeled HIV-1 CA were obtained with a Thermo MSQ Plus single quadrupole mass spectrometer, also operating in positive ion mode and using electrospray ionization. Sample introduction was via a Thermo Acclaim Pepmap 300 C18 column (1.0 mm inner diameter and 150 mm in length), using a 0.2 ml/min flow rate and a solvent gradient from 88% water/12% acetonitrile to 34% water/66% acetonitrile (with 0.01% trifluoroacetic acid) in 22 min. The multi-charged m/z spectrum was deconvolved using the MagTran program. Expected and measured masses for NTD-labeled CA were 26695.8 Da and 26527 Da respectively. Expected and measured masses for CTD-labeled CA were 26282.85 Da and 26134 Da respectively. From these data, we infer isotopic enrichment levels of about 99.4% for both segmentally labeled products.