Which structure of Protein is not denatured after heating upto100 degree?

Primary structure of protein is not denatured after heating upto100 degree. Heat coagulation result in loss of higher level of structures other than primary structure. Difference between various protein structures Features 1o 2o 3o 4o Bond Covalent/ Peptide/ Amide Hydrogen- bond (H-bond) S~S HydrophobicHydrogenIonic HydrophobicH-bondIonic Functional activity Absent Absent Present Present Denaturation Retained because peptide bond is very strong. Lost Lost Lost Detection Mass Spectrometry, Edman's Technique x-ray crystallography - Best for crystallizable proteins)NMR spectrometry - Best for non- crystallizable proteins S-S stands for disulphide bond