Determination of the H^N–H^α Coupling Constant in Large Isotopically Enriched Proteins

The ³J H α, H N coupling constants of very large proteins can be determined independent of the width of the signal in the NMR experiments described here. Both pulse sequences correlating ¹⁵N with ¹³C^α and H^N were used to determine ³J H α, H N in the P13 domain of mannose permease. This coupling constant provides information on the range of values for the angle φ, which is important in molecular dynamics calculations.