Direct detection of lysine side chain NH3+ in protein–heparin complexes using NMR spectroscopy

Abstract

Two NMR observables, the N_ζH₃⁺ peak in the HISQC spectrum and N_ζ chemical shift difference between the free and heparin-bound forms, can identify binding-interface lysines in protein–heparin complexes. Unlike backbone chemical shifts, these direct probes are stringent and are less prone to either false positives or false negatives.