Protein provides protection to the human body
The skin's dense network of collagen fibers provides skin with structure and support and serves as a barricade against harmful substances. The critical components of enzymes and antibodies are proteins. The immune system depends on enzymes and antibodies to attack and destroy harmful invaders like bacteria, viruses, and other toxic substances. One example is an enzyme called lysozyme, which is secreted in the saliva and destroys the cell walls of bacteria, causing them to rupture.
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Specific proteins circulating in the blood can be directed to build a molecular knife that destroys the cellular membranes of the intruders. White blood cells secrete antibodies to look over carefully or inspect the entire circulatory system, locating and eliminating harmful bacteria and viruses. Antibodies also initiate other factors in the immune system to look for, identify, and destroy unwanted intruders.
Protein for Structure and motion, the collagen
The most abundant structural protein in the human body is collagen, which makes up about 6% of total body weight and 30% of bone tissues. Collagen is a tough, fibrous protein in a highly ordered structure. Collagen comprises large proportions of tendons, ligaments, cartilage, skin, and muscle.
Collagen makes bones strong but flexible. The closely packed collagen fibrils in ligaments and tendons allow for synchronous mechanical movements of muscles and bones and the ability of these tissues to spring back after a move or action is complete. Collagen fibers in the skin's dermis provide structure, and the accompanying elastin protein fibrils give it flexibility.
Collagen and elastin proteins secreted by the smooth-muscle cells surround blood vessels and provide structure and the capability of stretching back after blood is pumped through the blood vessels. Another structural fibrous protein is keratin. Keratin is what skin, hair, and nails are made of.