The 1000+1 model system simulates the typical human urine metabolome (Bouatra S. et al, The human urine metabolome. PLoS ONE 8, e73076, 2013) added by some sugars and testosterone (= the largest spin-system, with 23 particles). The spectral parameters are mainly from our own spectral analyses, from the spectral parameter prediction (Laatikainen R. et al, Comprehensive Strategy for Proton Chemical Shift Prediction: Linear Prediction with Non-Linear Corrections, J.Chem.Inf.Model., 2014, 54, 419) and from analyses of HMDB spectra. Because the variable origin of the parameters, the present model cannot be used for demanding analyses – our purpose was just to demonstrate the potential of qQMSA and report the largest N-spin QM simulation ever done.
1 Spin-Particle = A, A2, A3, AA’, 2*A3,.. spin-system, nuclei with identical shifts and couplings.
2 Compound means a single compound like glucose, which is composed of A- and B-glucose molecules the ratio of which is fixed.
3 There are also some compounds with protons coupled to 31P and 14N species.
4 The simulation time (< 8 sec) includes the system packing, the QM mechanical calculations and the line-shape simulation. The time used for one iteration cycle (which allows adjustment of shifts and line-shapes) is about the same or larger. The simplest way to use the model is regression analysis, which takes 10 - 15 sec/spectrum – but suffers from chemical shift variations if the sample chemical shifts are not very similar to those used for the model. These variations can be reduced by broadening, but it mixes populations of similar compounds – yielding descriptors that may be useful, anyway. See also Multitasking QMSA .