Method (s) to determine protein structure is/are
X-ray crystallography (X-ray diffraction)
UV light spectroscopy and infra-red spectroscopy
Nuclear magnetic resonance (NMR) spectroscopy
Polychromatic X-ray crystallography (Laue diffraction)  
Optical rotatory dispersion
Circular dichroism
Computer-based modelling
Mass spectrometry
X-Ray Crystallography
NMR Spectroscopy
Infrared spectroscopy
All of these