Unit resolution mass spectra of 112 kDa molecules with 3 Da accuracy

Previously, the highest molecular weight for a sample yielding a unit resolution mass spectrum was 67 kDa (marginal at 86 kDa), obtained with a 6.2 T Fourier-transform mass spectrometer with electrospray ionization. Now with a 9.4 T instrument, resolving power of 170,000 has been achieved for chondroitinase I (997 amino acids) and II (990 amino acids), making possible molecular weight assignments of 112,509 and 111,714, respectively, versus 112,508 and 111,713 calculated. Assisting these assignments was the noise reduction in the resolved isotopic peaks achieved by the time domain data sampling technique introduced by Senko, Marshall, and co-workers.