All proteins are not biocatalysts. Denaturation of proteins affects only secondary and fertiary structures. The most commonly used method for determining the C-terminal amino acid residue in a protein is hydrazinolysis. In this method, protein is treated with anhydrous hydrazine at 373K when all amino acid residues except C-terminal one is converted into amino acid hydrazides. The mixture of products is subjected to chromatography. On elution the strongly basic hydrazides are retained, but the free amino acid is eluted. By identifying the free amino acid the C-terminal amino acid residue of a protein can be determined. The first β-pleated sheet structure was proposed by ω. Astburry while a refined version was proposed by Linus pauling and Robert corey.