1H‐NMR sequential assignments and cation‐binding studies of spinach plastocyanin

Abstract

The essentially complete assignment of the 1H‐NMR spectrum of the Cu(I) form of spinach plastocyanin has been achieved using two‐dimensional NMR techniques and sequence‐specific resonance assignment procedures. A variety of pH and temperature conditions was utilised to overcome the problems of resonance overlap in the spectrum, degeneracy of CαH and solvent H2O chemical shifts, and cross‐saturation of labile NH resonances. A qualitative analysis of the long‐range nuclear Overhauser effects observed indicates that the backbone fold of spinach plastocyanin is very similar to that of poplar plastocyanin, whose structure has been solved by X‐ray crystallography and differs in 22 of its 99 amino acid residues. The assignments provide a basis for further investigations into the structural and ion‐ and protein‐binding properties of plastocyanin in solution. Copyright © 1987, Wiley Blackwell. All rights reserved