All of the following can determine the protein structure, EXCEPT:

HPLC is a technique used for enhanced and precise separation of even small amounts of biological and nonbiological molecules. It is a form of column chromatography used to separate, identify, and purify compounds.Must know:Mass spectrometry: The superior sensitivity, speed, and versatility of MS have replaced the Edman technique as the principal method for determining the sequences of peptides and proteins.X-ray crystallography: x-ray crystallography revealed the structures of thousands of biological macromolecules ranging from proteins to many oligonucleotides and a few viruses.Nuclear magnetic resonance (NMR) spectroscopy: Nuclear magnetic resonance (NMR) spectroscopy, a powerful complement to x-ray crystallography, measures the absorbance of radio frequency electromagnetic energy by ceain atomic nuclei. NMR spectroscopy analyzes proteins in aqueous solution. Not only does this obte the need to form crystals (a paicular advantage when dealing with difficult to crystallize membrane proteins), it renders possible real-time observation of the changes in conformation that accompany ligand binding or catalysis. Ref: Kennelly P.J., Rodwell V.W. (2011). Chapter 5. Proteins: Higher Orders of Structure. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.