Denaturation of a protein results in the loss of its secondary and tertiary structures, which leads to the loss of its biological activity, making it inactive rather than more active. For instance, enzymes (which are proteins) get denatured and destroyed at high temperatures. The other statements are correct: Insulin is a peptide hormone that maintains glucose homeostasis in the blood; Ovalbumin is the main protein found in egg white acting as a food reserve; and Fibrinogen (converted by thrombin) is a plasma protein essential for the coagulation or clotting of blood.